This class contains the quintic Bezier curves, x(u) and y(u), that have been created by SmoothSegmentedFunctionFactory to follow a physiologically meaningful muscle characteristic. More...

Inheritance diagram for OpenSim::SmoothSegmentedFunction:

Public Member Functions
	SmoothSegmentedFunction ()
	The default constructor, which populates the member data fields with NaN's. More...

double	calcValue (double x) const
	Calculates the value of the curve this object represents. More...

double	calcDerivative (double x, int order) const
	Calculates the value of the derivative of the curve this object represents. More...

double	calcIntegral (double x) const
	This will return the value of the integral of this objects curve evaluated at x. More...

bool	isIntegralAvailable () const
	Returns a bool that indicates if the integral curve has been computed. More...

bool	isIntegralComputedLeftToRight () const
	Returns a bool that indicates if the integral computed is computed left to right, or right to left. More...

std::string	getName () const
	Returns a string that is the name for this curve, which is set at the time of construction and cannot be changed after construction. More...

void	setName (std::string &name)

SimTK::Vec2	getCurveDomain () const
	This function returns a SimTK::Vec2 that contains in its 0th element the lowest value of the curve domain, and in its 1st element the highest value in the curve domain of the curve. More...

void	printMuscleCurveToCSVFile (const std::string &path, double domainMin, double domainMax) const
	This function will generate a csv file (of 'name_curveName.csv', where name is the one used in the constructor) of the muscle curve, and 'curveName' corresponds to the function that was called from SmoothSegmentedFunctionFactory to create the curve. More...

Detailed Description

This class contains the quintic Bezier curves, x(u) and y(u), that have been created by SmoothSegmentedFunctionFactory to follow a physiologically meaningful muscle characteristic.

A SmoothSegmentedFunction cannot be created directly, you must use SmoothSegmentedFunctionFactory to create the muscle curve of interest.

Future Upgrades

Add a hint object to keep the last u that corresponded to the location of interest to prevent unnecessary redundant evaluations of u. This hint could be similar in form to the used by the SimTK::BicubicSurface class

Computational Cost Details All computational costs assume the following operation costs:

    Operation Type   : #flops
    +,-,=,Boolean Op : 1 
                   / : 10
                 sqrt: 20
                 trig: 40

These relative weightings will vary processor to processor, and so any of the quoted computational costs are approximate.

Author: Matt Millard

Version: 0.0

Constructor & Destructor Documentation

◆ SmoothSegmentedFunction()

OpenSim::SmoothSegmentedFunction::SmoothSegmentedFunction ( )

The default constructor, which populates the member data fields with NaN's.

Member Function Documentation

◆ calcDerivative()

double OpenSim::SmoothSegmentedFunction::calcDerivative	(	double	x,
		int	order
	)		const

Calculates the value of the derivative of the curve this object represents.

Parameters

x	The domain point of interest.
order	The order of the derivative to compute. Note that order must be between 0 and 2. Calling 0 just calls calcValue.

Exceptions

OpenSim::Exception -If anything but 0's are stored in derivComponents -If more than the 6th derivative is asked for -If ax has a size other than 1

Returns: The value of the d^ny/dx^n th derivative evaluated at x

Computational Costs

     x in curve domain  : ~391 flops
     x in linear section:   ~2 flops

◆ calcIntegral()

double OpenSim::SmoothSegmentedFunction::calcIntegral ( double x ) const

This will return the value of the integral of this objects curve evaluated at x.

Parameters

x	the domain point of interest

Exceptions

OpenSim::Exception -If the function does not have a pre-computed integral

Returns: the value of the functions integral evaluated at x

The integral is approximate, though its errors are small. The integral is computed by numerically integrating the function when the constructor for this class is called (if computeIntegral is true) and then splining the result, thus the regions between the knot points may have some error in them. A very fine mesh of points is used to create the spline so the errors will be small

Computational Costs

     x in curve domain  : ~13 flops
     x in linear section: ~19 flops

◆ calcValue()

double OpenSim::SmoothSegmentedFunction::calcValue ( double x ) const

Calculates the value of the curve this object represents.

Parameters

x	The domain point of interest

Exceptions

OpenSim::Exception -If ax does not have a size of 1

Returns: The value of the curve

The curve is parameterized as a set of Bezier curves. If x is within the domain of these Bezier curves they will be evaluated. If x is outside of the domain of these Bezier curves a linear extrapolation will be evaluated

Computational Costs

     x in curve domain  : ~282 flops
     x in linear section:   ~5 flops

◆ getCurveDomain()

SimTK::Vec2 OpenSim::SmoothSegmentedFunction::getCurveDomain ( ) const

This function returns a SimTK::Vec2 that contains in its 0th element the lowest value of the curve domain, and in its 1st element the highest value in the curve domain of the curve.

Outside of this domain the curve is approximated using linear extrapolation.

Returns: The minimum and maximum value of the domain, x, of the curve y(x). Within this range y(x) is a curve, outside of this range the function y(x) is a C2 (continuous to the second derivative) linear extrapolation

◆ getName()

std::string OpenSim::SmoothSegmentedFunction::getName ( ) const

Returns a string that is the name for this curve, which is set at the time of construction and cannot be changed after construction.

Returns: The string name this object was given during construction

◆ isIntegralAvailable()

bool OpenSim::SmoothSegmentedFunction::isIntegralAvailable ( ) const

Returns a bool that indicates if the integral curve has been computed.

Returns: true if the integral of this function is available, false if it has not been computed.

◆ isIntegralComputedLeftToRight()

bool OpenSim::SmoothSegmentedFunction::isIntegralComputedLeftToRight ( ) const

Returns a bool that indicates if the integral computed is computed left to right, or right to left.

Returns: true if the integral was computed left to right, and false if the integral was computed right to left. Note that the output of this function is only valid if isIntegralAvailable() returns true.

◆ printMuscleCurveToCSVFile()

void OpenSim::SmoothSegmentedFunction::printMuscleCurveToCSVFile	(	const std::string &	path,
		double	domainMin,
		double	domainMax
	)		const

This function will generate a csv file (of 'name_curveName.csv', where name is the one used in the constructor) of the muscle curve, and 'curveName' corresponds to the function that was called from SmoothSegmentedFunctionFactory to create the curve.

Parameters

path	The full path to the location. Note '/' slashes must be used, and do not put a '/' after the last folder.
domainMin	the left most domain point of the curve to print. The curve will extend to at least this point.
domainMax	the right most domain point of the curve to print. The printed curve will extend at least to this point, perhaps beyond.

Exceptions

OpenSim::Exception -If the filename is empty

For example the tendon curve for a muscle named 'glutmax' will be:

'glutmax_tendonForceLengthCurve.csv'

The file will contain the following columns:

Col# 1, 2,     3,       4,  5
     x, y, dy/dx, d2y/dx2,  iy

Where iy is the integral of y(x). If the curve has been set not to have an integral, this column will not exist.

The curve will be sampled from its linear extrapolation region, through the curve, out to the other linear extrapolation region. The width of each linear extrapolation region is 10% of the entire range of x, or 0.1*(x1-x0).

The number of rows used will vary from curve to curve. Each quintic Bezier curve section will have 100 samples. Each linearly extrapolated region will have 10 samples each. Some muscle curves (the tendon, parallel elements, compressive elements) consist of only 1 elbow, and so these matrices will have only 100+20 rows. The force velocity curve is made up of 2 elbows and will have 200+20 rows. The active force length curve has 5 elbows, and so its sampled matrix will have 500+20 rows

Computational Costs This varies depending on the curve (as mentioned above).

     ~97,400 to 487,000 flops

Example To read the csv file with a header in from Matlab, you need to use csvread set so that it will ignore the header row. This is accomplished by using the extra two numerical arguments for csvread to tell the function to begin reading from the 1st row, and the 0th index (csvread is 0 indexed).

 data=csvread('test_tendonForceLengthCurve.csv',1,0);

◆ setName()

void OpenSim::SmoothSegmentedFunction::setName ( std::string & name )

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

OpenSim/Common/SmoothSegmentedFunction.h

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ SmoothSegmentedFunction()

Member Function Documentation

◆ calcDerivative()

◆ calcIntegral()

◆ calcValue()

◆ getCurveDomain()

◆ getName()

◆ isIntegralAvailable()

◆ isIntegralComputedLeftToRight()

◆ printMuscleCurveToCSVFile()

◆ setName()