Simbody  3.6
SimTK::Function_< T >::Step Class Reference

This is a Function_ subclass whose output value y=f(x) is smoothly stepped from y=y0 to y1 as its input argument goes from x=x0 to x1. More...

+ Inheritance diagram for SimTK::Function_< T >::Step:

Public Member Functions

 Step (const T &y0, const T &y1, Real x0, Real x1)
 Create a Function_::Step object that smoothly interpolates its output through a given range as its input moves through its range. More...
 
void setParameters (const T &y0, const T &y1, Real x0, Real x1)
 Change the four parameters that define the step function; see constructor for documentation. More...
 
calcValue (const Vector &xin) const override
 Calculate the value of this function at a particular point. More...
 
calcDerivative (const Array_< int > &derivComponents, const Vector &xin) const override
 Calculate a partial derivative of this function at a particular point. More...
 
int getArgumentSize () const override
 Get the number of components expected in the input vector. More...
 
int getMaxDerivativeOrder () const override
 Get the maximum derivative order this Function_ object can calculate. More...
 
Stepclone () const override
 Create a new heap-allocated copy of this concrete Function. More...
 
calcDerivative (const std::vector< int > &derivComponents, const Vector &x) const
 This provides compatibility with std::vector without requiring any copying. More...
 
- Public Member Functions inherited from SimTK::Function_< T >
virtual ~Function_ ()
 
calcDerivative (const std::vector< int > &derivComponents, const Vector &x) const
 This provides compatibility with std::vector without requiring any copying. More...
 

Detailed Description

template<class T>
class SimTK::Function_< T >::Step

This is a Function_ subclass whose output value y=f(x) is smoothly stepped from y=y0 to y1 as its input argument goes from x=x0 to x1.

This is an S-shaped function with first and second derivatives y'(x0)=y'(x1)=0 and y''(x0)=y''(x1)==0. The third derivative y''' exists and is continuous but we cannot guarantee anything about it at the end points.

Constructor & Destructor Documentation

◆ Step()

template<class T>
SimTK::Function_< T >::Step::Step ( const T &  y0,
const T &  y1,
Real  x0,
Real  x1 
)
inline

Create a Function_::Step object that smoothly interpolates its output through a given range as its input moves through its range.

Parameters
y0Output value when (x-x0)*sign(x1-x0) <= 0.
y1Output value when (x-x1)*sign(x1-x0) >= 0.
x0Start of switching interval.
x1End of switching interval (must not equal x0).
Template Parameters
TThe template type is the type of y0 and y1. This must be a type that supports subtraction and scalar multiplication by a Real so that we can compute an expression like y=y0 + f*(y1-y0) for some Real scalar f.

Note that the numerical values of x0 and x1 can be in either order x0 < x1 or x0 > x1, but they cannot be equal.

Member Function Documentation

◆ setParameters()

template<class T>
void SimTK::Function_< T >::Step::setParameters ( const T &  y0,
const T &  y1,
Real  x0,
Real  x1 
)
inline

Change the four parameters that define the step function; see constructor for documentation.

◆ calcValue()

template<class T>
T SimTK::Function_< T >::Step::calcValue ( const Vector x) const
inlineoverridevirtual

Calculate the value of this function at a particular point.

Parameters
xthe Vector of input arguments. Its size must equal the value returned by getArgumentSize().

Implements SimTK::Function_< T >.

◆ calcDerivative() [1/2]

template<class T>
T SimTK::Function_< T >::Step::calcDerivative ( const Array_< int > &  derivComponents,
const Vector x 
) const
inlineoverridevirtual

Calculate a partial derivative of this function at a particular point.

Which derivative to take is specified by listing the input components with which to take it. For example, if derivComponents=={0}, that indicates a first derivative with respective to component 0. If derivComponents=={0, 0, 0}, that indicates a third derivative with respective to component 0. If derivComponents=={4, 7}, that indicates a partial second derivative with respect to components 4 and 7.

Parameters
derivComponentsThe input components with respect to which the derivative should be taken. Its size must be less than or equal to the value returned by getMaxDerivativeOrder().
xThe Vector of input arguments. Its size must equal the value returned by getArgumentSize().
Returns
The value of the selected derivative, which is of type T.

Implements SimTK::Function_< T >.

◆ getArgumentSize()

template<class T>
int SimTK::Function_< T >::Step::getArgumentSize ( ) const
inlineoverridevirtual

Get the number of components expected in the input vector.

Implements SimTK::Function_< T >.

◆ getMaxDerivativeOrder()

template<class T>
int SimTK::Function_< T >::Step::getMaxDerivativeOrder ( ) const
inlineoverridevirtual

Get the maximum derivative order this Function_ object can calculate.

Implements SimTK::Function_< T >.

◆ clone()

template<class T>
Step* SimTK::Function_< T >::Step::clone ( ) const
inlineoverridevirtual

Create a new heap-allocated copy of this concrete Function.

For backwards compatibility this is not pure virtual; it has a default implementation that throws an exception if called. However, it should always be implemented.

Reimplemented from SimTK::Function_< T >.

◆ calcDerivative() [2/2]

template<class T>
T SimTK::Function_< T >::Step::calcDerivative ( const std::vector< int > &  derivComponents,
const Vector x 
) const
inline

This provides compatibility with std::vector without requiring any copying.


The documentation for this class was generated from the following file: