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JSBSim Flight Dynamics Model 1.0 (23 February 2013)
An Open Source Flight Dynamics and Control Software Library in C++
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JSBSim Flight Dynamics Model 1.0 (23 February 2013)
An Open Source Flight Dynamics and Control Software Library in C++
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Represents a mathematical function. More...
#include <FGFunction.h>
Inheritance diagram for FGFunction: Collaboration diagram for FGFunction:Public Member Functions | |
| FGFunction (FGPropertyManager *PropertyManager, Element *element, const std::string &prefix="") | |
| Constructor. | |
| virtual | ~FGFunction () |
| Destructor. | |
| void | cacheValue (bool shouldCache) |
| Specifies whether to cache the value of the function, so it is calculated only once per frame. | |
| std::string | GetName (void) const |
| Retrieves the name of the function. | |
| double | GetValue (void) const |
| Retrieves the value of the function object. | |
| std::string | GetValueAsString (void) const |
| The value that the function evaluates to, as a string. | |
The FGFunction class is a powerful and versatile resource that allows algebraic functions to be defined in a JSBSim configuration file. It is similar in concept to MathML (Mathematical Markup Language, www.w3.org/Math/), but simpler and more terse. A function definition consists of an operation, a value, a table, or a property (which evaluates to a value). The currently supported operations are:
An operation is defined in the configuration file as in the following example:
<sum>
<value> 3.14159 </value>
<property> velocities/qbar </property>
<product>
<value> 0.125 </value>
<property> metrics/wingarea </property>
</product>
</sum>
A full function definition, such as is used in the aerodynamics section of a configuration file includes the function element, and other elements. It should be noted that there can be only one non-optional (non-documentation) element - that is, one operation element - in the top-level function definition. Multiple value and/or property elements cannot be immediate child members of the function element. Almost always, the first operation within the function element will be a product or sum. For example:
<function name="aero/moment/Clr"> <description>Roll moment due to yaw rate</description> <product> <property>aero/qbar-area</property> <property>metrics/bw-ft</property> <property>aero/bi2vel</property> <property>velocities/r-aero-rad_sec</property> <table> <independentVar>aero/alpha-rad</independentVar> <tableData> 0.000 0.08 0.094 0.19 </tableData> </table> </product> </function>
The "lowest level" in a function is always a value or a property, which cannot itself contain another element. As shown, operations can contain values, properties, tables, or other operations. In the first above example, the sum element contains all three. What is evaluated is written algebraically as:
3.14159 + qbar + (0.125 * wingarea)
Some operations can take only a single argument. That argument, however, can be an operation (such as sum) which can contain other items. The point to keep in mind is that it evaluates to a single value - which is just what the trigonometric functions require (except atan2, which takes two arguments).
Note: In the definitions below, a "property" refers to a single property specified within either the <property></property> tag or the shortcut tag, <p></p>. The keyword "value" refers to a single numeric value specified either within the <value></value> tag or the shortcut <v></v> tag. The keyword "table" refers to a single table specified either within the <table></table> tag or the shortcut <t></t> tag. The plural form of any of the three words refers to one or more instances of a property, value, or table.
<sum>
{properties, values, tables, or other function elements}
</sum>
Example: Mach + 0.01
<sum>
<p> velocities/mach </p>
<v> 0.01 </v>
</sum>
<difference>
{properties, values, tables, or other function elements}
</difference>
Example: Mach - 0.01
<difference>
<p> velocities/mach </p>
<v> 0.01 </v>
</difference>
<product>
{properties, values, tables, or other function elements}
</product>
Example: qbar*S*beta*CY_beta
<product>
<property> aero/qbar-psf </property>
<property> metrics/Sw-sqft </property>
<property> aero/beta-rad </property>
<property> aero/coefficient/CY_beta </property>
</product>
<quotient>
{property, value, table, or other function element}
{property, value, table, or other function element}
</quotient>
Example: (2*GM)/R
<quotient>
<product>
<v> 2.0 </v>
<p> guidance/executive/gm </p>
</product>
<p> position/radius-to-vehicle-ft </p>
</quotient>
<pow>
{property, value, table, or other function element}
{property, value, table, or other function element}
</pow>
Example: Mach^2
<pow>
<p> velocities/mach </p>
<v> 2.0 </v>
</pow>
<sqrt>
{property, value, table, or other function element}
</sqrt>
Example: square root of 25
<sqrt> <v> 25.0 </v> </sqrt>
<toradians>
{property, value, table, or other function element}
</toradians>
Example: convert 45 degrees to radians
<toradians> <v> 45 </v> </toradians>
<todegrees>
{property, value, table, or other function element}
</todegrees>
Example: convert 0.5*pi radians to degrees
<todegrees>
<product> <v> 0.5 </v> <pi/> </product>
</todegrees>
<exp>
{property, value, table, or other function element}
</exp>
Example: raise "e" to the 1.5 power, e^1.5
<exp> <v> 1.5 </v> </exp>
<log2>
{property, value, table, or other function element}
</log2>
Example:
<log2> <v> 128 </v> </log2>
<ln>
{property, value, table, or other function element}
</ln>
Example: ln(128)
<ln> <v> 200 </v> </ln>
<log10>
{property, value, table, or other function element}
</log10>
Example log(Mach)
<log10> <p> velocities/mach </p> </log10>
<abs>
{property, value, table, or other function element}
</abs>
Example:
<abs> <p> flight-path/gamma-rad </p> </abs>
<sin>
{property, value, table, or other function element}
</sin>
Example:
<sin> <toradians> <p> fcs/heading-true-degrees </p> </toradians> </sin>
<cos>
{property, value, table, or other function element}
</cos>
Example:
<cos> <toradians> <p> fcs/heading-true-degrees </p> </toradians> </cos>
<tan>
{property, value, table, or other function element}
</tan>
Example:
<tan> <toradians> <p> fcs/heading-true-degrees </p> </toradians> </tan>
<asin>
{property, value, table, or other function element}
</asin>
Example:
<asin> <v> 0.5 </v> </asin>
<acos>
{property, value, table, or other function element}
</acos>
Example:
<acos> <v> 0.5 </v> </acos>
<atan>
{property, value, table, or other function element}
</atan>
Example:
<atan> <v> 0.5 </v> </atan>
<atan2>
{property, value, table, or other function element} {property, value, table, or other function element}
</atan2>
Example: inverse tangent of 0.5/0.25, evaluates to: 1.107 radians
<atan2> <v> 0.5 </<v> <v> 0.25 </v> </atan2>
<min>
{properties, values, tables, or other function elements}
</min>
Example: returns the lesser of velocity and 2500
<min>
<p> velocities/eci-velocity-mag-fps </p>
<v> 2500.0 </v>
</min>
<max>
{properties, values, tables, or other function elements}
</max>
Example: returns the greater of velocity and 15000
<max>
<p> velocities/eci-velocity-mag-fps </p>
<v> 15000.0 </v>
</max>
<avg>
{properties, values, tables, or other function elements}
</avg>
Example: returns the average of the four numbers below, evaluates to 0.50.
<avg>
<v> 0.25 </v>
<v> 0.50 </v>
<v> 0.75 </v>
<v> 0.50 </v>
</avg>
<fraction>
{property, value, table, or other function element}
</fraction>
Example: returns the fractional part of pi - or, roughly, 0.1415926...
<fraction> <pi/> </fraction>
<integer>
{property, value, table, or other function element}
</integer>
<mod>
{property, value, table, or other function element} {property, value, table, or other function element}
</mod>
Example: 5 mod 2, evaluates to 1
<mod> <v> 5 </v> <v> 2 </v> </mod>
<lt>
{property, value, table, or other function element}
{property, value, table, or other function element}
</lt>
Example: returns 1 if thrust is less than 10,000, returns 0 otherwise
<lt>
<p> propulsion/engine[2]/thrust-lbs </p>
<v> 10000.0 </v>
</lt>
<le>
{property, value, table, or other function element}
{property, value, table, or other function element}
</le>
Example: returns 1 if thrust is less than or equal to 10,000, returns 0 otherwise
<le>
<p> propulsion/engine[2]/thrust-lbs </p>
<v> 10000.0 </v>
</le>
<gt>
{property, value, table, or other function element}
{property, value, table, or other function element}
</gt>
Example: returns 1 if thrust is greater than 10,000, returns 0 otherwise
<gt>
<p> propulsion/engine[2]/thrust-lbs </p>
<v> 10000.0 </v>
</gt>
<ge>
{property, value, table, or other function element}
{property, value, table, or other function element}
</ge>
Example: returns 1 if thrust is greater than or equal to 10,000, returns 0 otherwise
<ge>
<p> propulsion/engine[2]/thrust-lbs </p>
<v> 10000.0 </v>
</ge>
<eq>
{property, value, table, or other function element}
{property, value, table, or other function element}
</eq>
Example: returns 1 if thrust is equal to 10,000, returns 0 otherwise
<eq>
<p> propulsion/engine[2]/thrust-lbs </p>
<v> 10000.0 </v>
</eq>
<nq>
{property, value, table, or other function element}
{property, value, table, or other function element}
</nq>
Example: returns 1 if thrust is not 0, returns 0 otherwise
<nq>
<p> propulsion/engine[2]/thrust-lbs </p>
<v> 0.0 </v>
</nq>
<and>
{properties, values, tables, or other function elements}
</and>
Example: returns 1 if the specified flags are all 1
<and>
<p> guidance/first-stage-flight-flag </p>
<p> control/engines-running-flag </p>
</and>
<or>
{properties, values, tables, or other function elements}
</or>
Example: returns 1 if any of the specified flags are 1
<or>
<p> guidance/first-stage-flight-flag </p>
<p> control/engines-running-flag </p>
</or>
<not>
{property, value, table, or other function element}
</not>
Example: returns 0 if the value of the supplied flag is 1
<not> <p> guidance/first-stage-flight-flag </p> </not>
<ifthen>
{property, value, table, or other function element}
{property, value, table, or other function element}
{property, value, table, or other function element}
</ifthen>
Example: if flight-mode is greater than 2, then a value of 0.00 is returned,
otherwise the value of the property control/pitch-lag is returned.
<ifthen>
<gt> <p> executive/flight-mode </p> <v> 2 </v> </gt>
<v> 0.00 </v>
<p> control/pitch-lag </p>
</ifthen>
<switch> {property, value, table, or other function element} {property, value, table, or other function element} {property, value, table, or other function element} ... </switch> Example: if flight-mode is 2, the switch function returns 0.50 <switch> <p> executive/flight-mode </p> <v> 0.25 </v> <v> 0.50 </v> <v> 0.75 </v> <v> 1.00 </v> </switch>
<random/>
<urandom/>
<pi/>
<interpolate1d>
{property, value, table, or other function element}
{property, value, table, or other function element} {property, value, table, or other function element}
...
</interpolate1d>
Example: If mach is 0.4, the interpolation will return 0.375. If mach is 1.5, the interpolation
will return 0.60.
<interpolate1d>
<p> velocities/mach </p>
<v> 0.00 </v> <v> 0.25 </v>
<v> 0.80 </v> <v> 0.50 </v>
<v> 0.90 </v> <v> 0.60 </v>
</interpolate1d>
Definition at line 699 of file FGFunction.h.
| FGFunction | ( | FGPropertyManager * | PropertyManager, |
| Element * | element, | ||
| const std::string & | prefix = "" |
||
| ) |
When this constructor is called, the XML element pointed to in memory by the element argument is traversed. If other FGParameter-derived objects (values, functions, properties, or tables) are encountered, this instance of the FGFunction object will store a pointer to the found object and pass the relevant Element pointer to the constructor for the new object. In other words, each FGFunction object maintains a list of "child" FGParameter-derived objects which in turn may each contain its own list, and so on. At runtime, each object evaluates its child parameters, which each may have its own child parameters to evaluate.
| PropertyManager | a pointer to the property manager instance. |
| element | a pointer to the Element object containing the function definition. |
| prefix | an optional prefix to prepend to the name given to the property that represents this function (if given). |
Definition at line 111 of file FGFunction.cpp.
References FGJSBBase::fgcyan, FGJSBBase::fgred, Element::GetAttributeValue(), Element::GetDataAsNumber(), Element::GetDataLine(), Element::GetElement(), Element::GetName(), Element::GetNextElement(), FGJSBBase::highint, and FGJSBBase::reset.
: PropertyManager(propMan), Prefix(prefix)
{
Element* element;
string operation, property_name;
cached = false;
cachedValue = -HUGE_VAL;
invlog2val = 1.0/log10(2.0);
pCopyTo = 0L;
Name = el->GetAttributeValue("name");
operation = el->GetName();
if (operation == function_string) {
sCopyTo = el->GetAttributeValue("copyto");
if (!sCopyTo.empty()) {
pCopyTo = PropertyManager->GetNode(sCopyTo);
if (pCopyTo == 0L) cerr << "Property \"" << sCopyTo << "\" must be previously defined in function "
<< Name << endl;
}
Type = eTopLevel;
} else if (operation == product_string) {
Type = eProduct;
} else if (operation == difference_string) {
Type = eDifference;
} else if (operation == sum_string) {
Type = eSum;
} else if (operation == quotient_string) {
Type = eQuotient;
} else if (operation == pow_string) {
Type = ePow;
} else if (operation == sqrt_string) {
Type = eSqrt;
} else if (operation == toradians_string) {
Type = eToRadians;
} else if (operation == todegrees_string) {
Type = eToDegrees;
} else if (operation == log2_string) {
Type = eLog2;
} else if (operation == ln_string) {
Type = eLn;
} else if (operation == log10_string) {
Type = eLog10;
} else if (operation == abs_string) {
Type = eAbs;
} else if (operation == sign_string) {
Type = eSign;
} else if (operation == sin_string) {
Type = eSin;
} else if (operation == exp_string) {
Type = eExp;
} else if (operation == cos_string) {
Type = eCos;
} else if (operation == tan_string) {
Type = eTan;
} else if (operation == asin_string) {
Type = eASin;
} else if (operation == acos_string) {
Type = eACos;
} else if (operation == atan_string) {
Type = eATan;
} else if (operation == atan2_string) {
Type = eATan2;
} else if (operation == min_string) {
Type = eMin;
} else if (operation == max_string) {
Type = eMax;
} else if (operation == avg_string) {
Type = eAvg;
} else if (operation == fraction_string) {
Type = eFrac;
} else if (operation == integer_string) {
Type = eInteger;
} else if (operation == mod_string) {
Type = eMod;
} else if (operation == random_string) {
Type = eRandom;
} else if (operation == urandom_string) {
Type = eUrandom;
} else if (operation == pi_string) {
Type = ePi;
} else if (operation == rotation_alpha_local_string) {
Type = eRotation_alpha_local;
} else if (operation == rotation_beta_local_string) {
Type = eRotation_beta_local;
} else if (operation == rotation_gamma_local_string) {
Type = eRotation_gamma_local;
} else if (operation == rotation_bf_to_wf_string) {
Type = eRotation_bf_to_wf;
} else if (operation == rotation_wf_to_bf_string) {
Type = eRotation_wf_to_bf;
} else if (operation == lessthan_string) {
Type = eLT;
} else if (operation == lessequal_string) {
Type = eLE;
} else if (operation == greatthan_string) {
Type = eGT;
} else if (operation == greatequal_string) {
Type = eGE;
} else if (operation == equal_string) {
Type = eEQ;
} else if (operation == notequal_string) {
Type = eNE;
} else if (operation == and_string) {
Type = eAND;
} else if (operation == or_string) {
Type = eOR;
} else if (operation == not_string) {
Type = eNOT;
} else if (operation == ifthen_string) {
Type = eIfThen;
} else if (operation == switch_string) {
Type = eSwitch;
} else if (operation == interpolate1d_string) {
Type = eInterpolate1D;
} else if (operation != description_string) {
cerr << "Bad operation " << operation << " detected in configuration file" << endl;
}
element = el->GetElement();
if (!element && Type != eRandom && Type != eUrandom && Type != ePi) {
cerr << fgred << highint << endl;
cerr << " No element was specified as an argument to the \"" << operation << "\" operation" << endl;
cerr << " This can happen when, for instance, a cos operation is specified and a " << endl;
cerr << " property name is given explicitly, but is not placed within a" << endl;
cerr << " <property></property> element tag pair." << endl;
cerr << reset;
exit(-2);
}
while (element) {
operation = element->GetName();
// data types
if (operation == property_string || operation == p_string) {
property_name = element->GetDataLine();
if (property_name.find("#") != string::npos) {
if (is_number(Prefix)) {
property_name = replace(property_name,"#",Prefix);
}
}
FGPropertyNode* newNode = 0L;
if (PropertyManager->HasNode(property_name)) {
newNode = PropertyManager->GetNode(property_name);
Parameters.push_back(new FGPropertyValue( newNode ));
} else {
cerr << fgcyan << "Warning: The property " + property_name + " is initially undefined."
<< reset << endl;
Parameters.push_back(new FGPropertyValue( property_name,
PropertyManager ));
}
} else if (operation == value_string || operation == v_string) {
Parameters.push_back(new FGRealValue(element->GetDataAsNumber()));
} else if (operation == table_string || operation == t_string) {
Parameters.push_back(new FGTable(PropertyManager, element));
// operations
} else if (operation == product_string ||
operation == difference_string ||
operation == sum_string ||
operation == quotient_string ||
operation == pow_string ||
operation == sqrt_string ||
operation == toradians_string ||
operation == todegrees_string ||
operation == exp_string ||
operation == log2_string ||
operation == ln_string ||
operation == log10_string ||
operation == abs_string ||
operation == sign_string ||
operation == sin_string ||
operation == cos_string ||
operation == tan_string ||
operation == asin_string ||
operation == acos_string ||
operation == atan_string ||
operation == atan2_string ||
operation == min_string ||
operation == max_string ||
operation == fraction_string ||
operation == integer_string ||
operation == mod_string ||
operation == random_string ||
operation == urandom_string ||
operation == pi_string ||
operation == avg_string ||
operation == rotation_alpha_local_string||
operation == rotation_beta_local_string||
operation == rotation_gamma_local_string||
operation == rotation_bf_to_wf_string||
operation == rotation_wf_to_bf_string ||
operation == lessthan_string ||
operation == lessequal_string ||
operation == greatthan_string ||
operation == greatequal_string ||
operation == equal_string ||
operation == notequal_string ||
operation == and_string ||
operation == or_string ||
operation == not_string ||
operation == ifthen_string ||
operation == switch_string ||
operation == interpolate1d_string)
{
Parameters.push_back(new FGFunction(PropertyManager, element, Prefix));
} else if (operation != description_string) {
cerr << "Bad operation " << operation << " detected in configuration file" << endl;
}
element = el->GetNextElement();
}
bind(); // Allow any function to save its value
Debug(0);
}
Here is the call graph for this function:| void cacheValue | ( | bool | shouldCache | ) |
If shouldCache is true, then the value of the function is calculated, and a flag is set so further calculations done this frame will use the cached value. In order to turn off caching, cacheValue must be called with a false argument.
| shouldCache | specifies whether the function should cache the computed value. |
Definition at line 336 of file FGFunction.cpp.
References FGFunction::GetValue().
{
cached = false; // Must set cached to false prior to calling GetValue(), else
// it will _never_ calculate the value;
if (cache) {
cachedValue = GetValue();
cached = true;
}
}
Here is the call graph for this function:| double GetValue | ( | void | ) | const [virtual] |
Implements FGParameter.
Definition at line 360 of file FGFunction.cpp.
Referenced by FGFunction::cacheValue(), FGRocket::Calculate(), FGBallonet::Calculate(), FGRocket::FGRocket(), FGFunction::GetValueAsString(), and FGAerodynamics::Run().
{
unsigned int i;
double scratch;
double temp=0;
if (cached) return cachedValue;
if ( Type != eRandom
&& Type != eUrandom
&& Type != ePi ) temp = Parameters[0]->GetValue();
switch (Type) {
case eTopLevel:
if (pCopyTo) pCopyTo->setDoubleValue(temp);
break;
case eProduct:
for (i=1;i<Parameters.size();i++) {
temp *= Parameters[i]->GetValue();
}
break;
case eSum:
for (i=1;i<Parameters.size();i++) {
temp += Parameters[i]->GetValue();
}
break;
case eQuotient:
if (Parameters[1]->GetValue() != 0.0)
temp /= Parameters[1]->GetValue();
else
temp = HUGE_VAL;
break;
case eDifference:
for (i=1;i<Parameters.size();i++) {
temp -= Parameters[i]->GetValue();
}
break;
case ePow:
temp = pow(temp,Parameters[1]->GetValue());
break;
case eSqrt:
temp = sqrt(temp);
break;
case eToRadians:
temp *= M_PI/180.0;
break;
case eToDegrees:
temp *= 180.0/M_PI;
break;
case eExp:
temp = exp(temp);
break;
case eLog2:
if (temp > 0.00) temp = log10(temp)*invlog2val;
else temp = -HUGE_VAL;
break;
case eLn:
if (temp > 0.00) temp = log(temp);
else temp = -HUGE_VAL;
break;
case eLog10:
if (temp > 0.00) temp = log10(temp);
else temp = -HUGE_VAL;
break;
case eAbs:
temp = fabs(temp);
break;
case eSign:
temp = temp < 0 ? -1:1; // 0.0 counts as positive.
break;
case eSin:
temp = sin(temp);
break;
case eCos:
temp = cos(temp);
break;
case eTan:
temp = tan(temp);
break;
case eACos:
temp = acos(temp);
break;
case eASin:
temp = asin(temp);
break;
case eATan:
temp = atan(temp);
break;
case eATan2:
temp = atan2(temp, Parameters[1]->GetValue());
break;
case eMod:
temp = ((int)temp) % ((int) Parameters[1]->GetValue());
break;
case eMin:
for (i=1;i<Parameters.size();i++) {
if (Parameters[i]->GetValue() < temp) temp = Parameters[i]->GetValue();
}
break;
case eMax:
for (i=1;i<Parameters.size();i++) {
if (Parameters[i]->GetValue() > temp) temp = Parameters[i]->GetValue();
}
break;
case eAvg:
for (i=1;i<Parameters.size();i++) {
temp += Parameters[i]->GetValue();
}
temp /= Parameters.size();
break;
case eFrac:
temp = modf(temp, &scratch);
break;
case eInteger:
modf(temp, &scratch);
temp = scratch;
break;
case eRandom:
temp = GaussianRandomNumber();
break;
case eUrandom:
temp = -1.0 + (((double)rand()/double(RAND_MAX))*2.0);
break;
case ePi:
temp = M_PI;
break;
case eLT:
temp = (temp < Parameters[1]->GetValue())?1:0;
break;
case eLE:
temp = (temp <= Parameters[1]->GetValue())?1:0;
break;
case eGT:
temp = (temp > Parameters[1]->GetValue())?1:0;
break;
case eGE:
temp = (temp >= Parameters[1]->GetValue())?1:0;
break;
case eEQ:
temp = (temp == Parameters[1]->GetValue())?1:0;
break;
case eNE:
temp = (temp != Parameters[1]->GetValue())?1:0;
break;
case eAND:
{
bool flag = (GetBinary(temp) != 0u);
for (i=1; i<Parameters.size() && flag; i++) {
flag = (GetBinary(Parameters[i]->GetValue()) != 0);
}
temp = flag ? 1 : 0;
}
break;
case eOR:
{
bool flag = (GetBinary(temp) != 0);
for (i=1; i<Parameters.size() && !flag; i++) {
flag = (GetBinary(Parameters[i]->GetValue()) != 0);
}
temp = flag ? 1 : 0;
}
break;
case eNOT:
temp = (GetBinary(temp) != 0) ? 0 : 1;
break;
case eIfThen:
{
i = Parameters.size();
if (i == 3) {
if (GetBinary(temp) == 1) {
temp = Parameters[1]->GetValue();
} else {
temp = Parameters[2]->GetValue();
}
} else {
throw("Malformed if/then function statement");
}
}
break;
case eSwitch:
{
unsigned int n = Parameters.size()-1;
i = int(temp+0.5);
if (i >= 0u && i < n) {
temp = Parameters[i+1]->GetValue();
} else {
throw(string("The switch function index selected a value above the range of supplied values"
" - not enough values were supplied."));
}
}
break;
case eInterpolate1D:
{
unsigned int sz = Parameters.size();
if (temp <= Parameters[1]->GetValue()) {
temp = Parameters[2]->GetValue();
} else if (temp >= Parameters[sz-2]->GetValue()) {
temp = Parameters[sz-1]->GetValue();
} else {
for (unsigned int i=1; i<=sz-4; i+=2) {
if (temp < Parameters[i+2]->GetValue()) {
double factor = (temp - Parameters[i]->GetValue()) /
(Parameters[i+2]->GetValue() - Parameters[i]->GetValue());
double span = Parameters[i+3]->GetValue() - Parameters[i+1]->GetValue();
double val = factor*span;
temp = Parameters[i+1]->GetValue() + val;
break;
}
}
}
}
break;
case eRotation_alpha_local:
if (Parameters.size()==6) // calculates local angle of attack for skydiver body component
//Euler angles from the intermediate body frame to the local body frame must be from a z-y-x axis rotation order
{
double alpha = Parameters[0]->GetValue()*degtorad;
double beta = Parameters[1]->GetValue()*degtorad;
double gamma = Parameters[2]->GetValue()*degtorad;
double phi = Parameters[3]->GetValue()*degtorad;
double theta = Parameters[4]->GetValue()*degtorad;
double psi = Parameters[5]->GetValue()*degtorad;
double cphi2 = cos(-phi/2), ctht2 = cos(-theta/2), cpsi2 = cos(-psi/2);
double sphi2 = sin(-phi/2), stht2 = sin(-theta/2), spsi2 = sin(-psi/2);
double calpha2 = cos(-alpha/2), salpha2 = sin(-alpha/2);
double cbeta2 = cos(beta/2), sbeta2 = sin(beta/2);
double cgamma2 = cos(-gamma/2), sgamma2 = sin(-gamma/2);
//calculate local body frame to the intermediate body frame rotation quaternion
double At = cphi2*ctht2*cpsi2 - sphi2*stht2*spsi2;
double Ax = cphi2*stht2*spsi2 + sphi2*ctht2*cpsi2;
double Ay = cphi2*stht2*cpsi2 - sphi2*ctht2*spsi2;
double Az = cphi2*ctht2*spsi2 + sphi2*stht2*cpsi2;
//calculate the intermediate body frame to global wind frame rotation quaternion
double Bt = calpha2*cbeta2*cgamma2 - salpha2*sbeta2*sgamma2;
double Bx = calpha2*cbeta2*sgamma2 + salpha2*sbeta2*cgamma2;
double By = calpha2*sbeta2*sgamma2 + salpha2*cbeta2*cgamma2;
double Bz = calpha2*sbeta2*cgamma2 - salpha2*cbeta2*sgamma2;
//multiply quaternions
double Ct = At*Bt - Ax*Bx - Ay*By - Az*Bz;
double Cx = At*Bx + Ax*Bt + Ay*Bz - Az*By;
double Cy = At*By - Ax*Bz + Ay*Bt + Az*Bx;
double Cz = At*Bz + Ax*By - Ay*Bx + Az*Bt;
//calculate alpha_local
temp = -atan2(2*(Cy*Ct-Cx*Cz),(Ct*Ct+Cx*Cx-Cy*Cy-Cz*Cz));
temp *= radtodeg;
} else {
temp = 1;
}
break;
case eRotation_beta_local:
if (Parameters.size()==6) // calculates local angle of sideslip for skydiver body component
//Euler angles from the intermediate body frame to the local body frame must be from a z-y-x axis rotation order
{
double alpha = Parameters[0]->GetValue()*degtorad; //angle of attack of intermediate body frame
double beta = Parameters[1]->GetValue()*degtorad; //sideslip angle of intermediate body frame
double gamma = Parameters[2]->GetValue()*degtorad; //roll angle of intermediate body frame
double phi = Parameters[3]->GetValue()*degtorad; //x-axis Euler angle from the intermediate body frame to the local body frame
double theta = Parameters[4]->GetValue()*degtorad; //y-axis Euler angle from the intermediate body frame to the local body frame
double psi = Parameters[5]->GetValue()*degtorad; //z-axis Euler angle from the intermediate body frame to the local body frame
double cphi2 = cos(-phi/2), ctht2 = cos(-theta/2), cpsi2 = cos(-psi/2);
double sphi2 = sin(-phi/2), stht2 = sin(-theta/2), spsi2 = sin(-psi/2);
double calpha2 = cos(-alpha/2), salpha2 = sin(-alpha/2);
double cbeta2 = cos(beta/2), sbeta2 = sin(beta/2);
double cgamma2 = cos(-gamma/2), sgamma2 = sin(-gamma/2);
//calculate local body frame to the intermediate body frame rotation quaternion
double At = cphi2*ctht2*cpsi2 - sphi2*stht2*spsi2;
double Ax = cphi2*stht2*spsi2 + sphi2*ctht2*cpsi2;
double Ay = cphi2*stht2*cpsi2 - sphi2*ctht2*spsi2;
double Az = cphi2*ctht2*spsi2 + sphi2*stht2*cpsi2;
//calculate the intermediate body frame to global wind frame rotation quaternion
double Bt = calpha2*cbeta2*cgamma2 - salpha2*sbeta2*sgamma2;
double Bx = calpha2*cbeta2*sgamma2 + salpha2*sbeta2*cgamma2;
double By = calpha2*sbeta2*sgamma2 + salpha2*cbeta2*cgamma2;
double Bz = calpha2*sbeta2*cgamma2 - salpha2*cbeta2*sgamma2;
//multiply quaternions
double Ct = At*Bt - Ax*Bx - Ay*By - Az*Bz;
double Cx = At*Bx + Ax*Bt + Ay*Bz - Az*By;
double Cy = At*By - Ax*Bz + Ay*Bt + Az*Bx;
double Cz = At*Bz + Ax*By - Ay*Bx + Az*Bt;
//calculate beta_local
temp = asin(2*(Cx*Cy+Cz*Ct));
temp *= radtodeg;
}
else //
{temp = 1;}
break;
case eRotation_gamma_local:
if (Parameters.size()==6) // calculates local angle of attack for skydiver body component
//Euler angles from the intermediate body frame to the local body frame must be from a z-y-x axis rotation order
{
double alpha = Parameters[0]->GetValue()*degtorad; //angle of attack of intermediate body frame
double beta = Parameters[1]->GetValue()*degtorad; //sideslip angle of intermediate body frame
double gamma = Parameters[2]->GetValue()*degtorad; //roll angle of intermediate body frame
double phi = Parameters[3]->GetValue()*degtorad; //x-axis Euler angle from the intermediate body frame to the local body frame
double theta = Parameters[4]->GetValue()*degtorad; //y-axis Euler angle from the intermediate body frame to the local body frame
double psi = Parameters[5]->GetValue()*degtorad; //z-axis Euler angle from the intermediate body frame to the local body frame
double cphi2 = cos(-phi/2), ctht2 = cos(-theta/2), cpsi2 = cos(-psi/2);
double sphi2 = sin(-phi/2), stht2 = sin(-theta/2), spsi2 = sin(-psi/2);
double calpha2 = cos(-alpha/2), salpha2 = sin(-alpha/2);
double cbeta2 = cos(beta/2), sbeta2 = sin(beta/2);
double cgamma2 = cos(-gamma/2), sgamma2 = sin(-gamma/2);
//calculate local body frame to the intermediate body frame rotation quaternion
double At = cphi2*ctht2*cpsi2 - sphi2*stht2*spsi2;
double Ax = cphi2*stht2*spsi2 + sphi2*ctht2*cpsi2;
double Ay = cphi2*stht2*cpsi2 - sphi2*ctht2*spsi2;
double Az = cphi2*ctht2*spsi2 + sphi2*stht2*cpsi2;
//calculate the intermediate body frame to global wind frame rotation quaternion
double Bt = calpha2*cbeta2*cgamma2 - salpha2*sbeta2*sgamma2;
double Bx = calpha2*cbeta2*sgamma2 + salpha2*sbeta2*cgamma2;
double By = calpha2*sbeta2*sgamma2 + salpha2*cbeta2*cgamma2;
double Bz = calpha2*sbeta2*cgamma2 - salpha2*cbeta2*sgamma2;
//multiply quaternions
double Ct = At*Bt - Ax*Bx - Ay*By - Az*Bz;
double Cx = At*Bx + Ax*Bt + Ay*Bz - Az*By;
double Cy = At*By - Ax*Bz + Ay*Bt + Az*Bx;
double Cz = At*Bz + Ax*By - Ay*Bx + Az*Bt;
//calculate local roll anlge
temp = -atan2(2*(Cx*Ct-Cz*Cy),(Ct*Ct-Cx*Cx+Cy*Cy-Cz*Cz));
temp *= radtodeg;
}
else //
{temp = 1;}
break;
case eRotation_bf_to_wf:
if (Parameters.size()==7) // transforms the input vector from a body frame to a wind frame. The origin of the vector remains the same.
{
double rx = Parameters[0]->GetValue(); //x component of input vector
double ry = Parameters[1]->GetValue(); //y component of input vector
double rz = Parameters[2]->GetValue(); //z component of input vector
double alpha = Parameters[3]->GetValue()*degtorad; //angle of attack of the body frame
double beta = Parameters[4]->GetValue()*degtorad; //sideslip angle of the body frame
double gamma = Parameters[5]->GetValue()*degtorad; //roll angle of the body frame
double index = Parameters[6]->GetValue();
double calpha2 = cos(-alpha/2), salpha2 = sin(-alpha/2);
double cbeta2 = cos(beta/2), sbeta2 = sin(beta/2);
double cgamma2 = cos(-gamma/2), sgamma2 = sin(-gamma/2);
//calculate the body frame to wind frame quaternion
double qt = calpha2*cbeta2*cgamma2 - salpha2*sbeta2*sgamma2;
double qx = calpha2*cbeta2*sgamma2 + salpha2*sbeta2*cgamma2;
double qy = calpha2*sbeta2*sgamma2 + salpha2*cbeta2*cgamma2;
double qz = calpha2*sbeta2*cgamma2 - salpha2*cbeta2*sgamma2;
//calculate the quaternion conjugate
double qstart = qt;
double qstarx = -qx;
double qstary = -qy;
double qstarz = -qz;
//multiply quaternions v*q
double vqt = -rx*qx - ry*qy - rz*qz;
double vqx = rx*qt + ry*qz - rz*qy;
double vqy = -rx*qz + ry*qt + rz*qx;
double vqz = rx*qy - ry*qx + rz*qt;
//multiply quaternions qstar*vq
double Cx = qstart*vqx + qstarx*vqt + qstary*vqz - qstarz*vqy;
double Cy = qstart*vqy - qstarx*vqz + qstary*vqt + qstarz*vqx;
double Cz = qstart*vqz + qstarx*vqy - qstary*vqx + qstarz*vqt;
if (index == 1) temp = Cx;
else if (index ==2) temp = Cy;
else temp = Cz;
}
else //
{temp = 1;}
break;
case eRotation_wf_to_bf:
if (Parameters.size()==7) // transforms the input vector from q wind frame to a body frame. The origin of the vector remains the same.
{
double rx = Parameters[0]->GetValue(); //x component of input vector
double ry = Parameters[1]->GetValue(); //y component of input vector
double rz = Parameters[2]->GetValue(); //z component of input vector
double alpha = Parameters[3]->GetValue()*degtorad; //angle of attack of the body frame
double beta = Parameters[4]->GetValue()*degtorad; //sideslip angle of the body frame
double gamma = Parameters[5]->GetValue()*degtorad; //roll angle of the body frame
double index = Parameters[6]->GetValue();
double calpha2 = cos(alpha/2), salpha2 = sin(alpha/2);
double cbeta2 = cos(-beta/2), sbeta2 = sin(-beta/2);
double cgamma2 = cos(gamma/2), sgamma2 = sin(gamma/2);
//calculate the wind frame to body frame quaternion
double qt = cgamma2*cbeta2*calpha2 + sgamma2*sbeta2*salpha2;
double qx = -cgamma2*sbeta2*salpha2 + sgamma2*cbeta2*calpha2;
double qy = cgamma2*cbeta2*salpha2 - sgamma2*sbeta2*calpha2;
double qz = cgamma2*sbeta2*calpha2 + sgamma2*cbeta2*salpha2;
//calculate the quaternion conjugate
double qstart = qt;
double qstarx = -qx;
double qstary = -qy;
double qstarz = -qz;
//multiply quaternions v*q
double vqt = -rx*qx - ry*qy - rz*qz;
double vqx = rx*qt + ry*qz - rz*qy;
double vqy = -rx*qz + ry*qt + rz*qx;
double vqz = rx*qy - ry*qx + rz*qt;
//multiply quaternions qstar*vq
double Cx = qstart*vqx + qstarx*vqt + qstary*vqz - qstarz*vqy;
double Cy = qstart*vqy - qstarx*vqz + qstary*vqt + qstarz*vqx;
double Cz = qstart*vqz + qstarx*vqy - qstary*vqx + qstarz*vqt;
if (index == 1) temp = Cx;
else if (index ==2) temp = Cy;
else temp = Cz;
}
else //
{temp = 1;}
break;
default:
cerr << "Unknown function operation type" << endl;
break;
}
return temp;
}
Here is the caller graph for this function:| string GetValueAsString | ( | void | ) | const |
Definition at line 773 of file FGFunction.cpp.
References FGFunction::GetValue().
{
ostringstream buffer;
buffer << setw(9) << setprecision(6) << GetValue();
return buffer.str();
}
Here is the call graph for this function: