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/* -------------------------------------------------------------------------- *
* Simbody(tm) Example: Simple Differentiator *
* -------------------------------------------------------------------------- *
* This is part of the SimTK biosimulation toolkit originating from *
* Simbios, the NIH National Center for Physics-Based Simulation of *
* Biological Structures at Stanford, funded under the NIH Roadmap for *
* Medical Research, grant U54 GM072970. See https://simtk.org/home/simbody. *
* *
* Portions copyright (c) 2006-12 Stanford University and the Authors. *
* Authors: Michael Sherman *
* Contributors: *
* *
* Licensed under the Apache License, Version 2.0 (the "License"); you may *
* not use this file except in compliance with the License. You may obtain a *
* copy of the License at http://www.apache.org/licenses/LICENSE-2.0. *
* *
* Unless required by applicable law or agreed to in writing, software *
* distributed under the License is distributed on an "AS IS" BASIS, *
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
* See the License for the specific language governing permissions and *
* limitations under the License. *
* -------------------------------------------------------------------------- */
/**@file
* This is a test program which uses the Differentiator class in various ways.
*/
//#define SimTK_USE_STATIC_LIBRARIES
#include "SimTKmath.h"
// Just so we can get the version number:
#include "SimTKlapack.h"
#include <cstdio>
#include <iostream>
using namespace SimTK;
// This is a system of functions of a particular set of parameters (state).
// The underlying function wants time also, so we provide that as data in
// the concrete class. Time should be set prior to calculation of the Jacobian.
class MyVectorFunc : public Differentiator::JacobianFunction {
public:
MyVectorFunc(int nf, int ny)
: Differentiator::JacobianFunction(nf,ny), time(0) { }
void setTime(Real t) {time=t;}
Real getTime() const {return time;}
// Must provide this pure virtual function.
int f(const Vector& y, Vector& fy) const override;
private:
Real time;
};
// This is a single scalar function of a vector of parameters.
class MyObjectiveFunc : public Differentiator::GradientFunction {
public:
MyObjectiveFunc(int ny)
: Differentiator::GradientFunction(ny), time(0) { }
void setTime(Real t) {time=t;}
Real getTime() const {return time;}
// Must provide this pure virtual function.
int f(const Vector& y, Real& fy) const override;
private:
Real time;
};
// This represents a generic scalar function of a scalar parameter,
// where the actual function has a simple C signature.
class GenericScalarFunc : public Differentiator::ScalarFunction {
typedef Real (*CFunc)(Real);
public:
GenericScalarFunc(CFunc cf)
: Differentiator::ScalarFunction(), cp(cf) { }
// Must provide this pure virtual function.
int f(Real x, Real& fx) const override {
fx = cp(x);
return 0;
}
CFunc cp;
};
class SinOmegaX : public Differentiator::ScalarFunction {
public:
SinOmegaX(Real omega) : w(omega) { }
// Must provide this virtual function.
int f(Real x, Real& fx) const override {
fx = std::sin(w*x);
return 0; // success
}
private:
const Real w;
};
int main () {
try {
const Real w=3;
SinOmegaX sinwx(w); // user-written class
Differentiator dsinwx(sinwx);
const Real x = 1.234;
Real exact = w*std::cos(w*x);
Real approx = dsinwx.calcDerivative(x);
std::printf("exact =%16.12f\n", exact);
std::printf("approx=%16.12f err=%.3e\n",
approx, std::abs((approx-exact)/exact));
return 0;
}
catch (std::exception& e) {
std::printf("FAILED: %s\n", e.what());
return 1;
}
}
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