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Changed: ScalarFunc is now a sub-class of utl::Function<Real,Real>.

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Added: Virtual method for calculation of derivative of scalar functions.
For expression functions the derivative can be evaluated through a separate
user-specified expression, or numerically by a finite difference approach.
This commit is contained in:
Knut Morten Okstad 2018-04-19 11:21:04 +02:00
parent d5fa8eac03
commit c0d97367eb
6 changed files with 167 additions and 44 deletions
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76
src/Utility/ExprFunctions.C
View File

@ -83,10 +83,12 @@ static void ExprException (const ExprEval::Exception& exc, const char* task,
EvalFunc::numError++;
}
int EvalFunc::numError = 0;
EvalFunc::EvalFunc (const char* function, const char* x)
EvalFunc::EvalFunc (const char* function, const char* x, Real eps)
: gradient(nullptr), dx(eps)
{
try {
size_t nalloc = 1;
@ -104,7 +106,7 @@ EvalFunc::EvalFunc (const char* function, const char* x)
v[i] = new ExprEval::ValueList;
f[i]->AddDefaultFunctions();
v[i]->AddDefaultValues();
v[i]->Add(x,0,false);
v[i]->Add(x,0.0,false);
expr[i]->SetFunctionList(f[i]);
expr[i]->SetValueList(v[i]);
expr[i]->Parse(function);
@ -112,7 +114,7 @@ EvalFunc::EvalFunc (const char* function, const char* x)
}
}
catch (ExprEval::Exception e) {
cleanup();
this->cleanup();
ExprException(e,"parsing",function);
}
}
@ -120,34 +122,42 @@ EvalFunc::EvalFunc (const char* function, const char* x)
EvalFunc::~EvalFunc ()
{
cleanup();
this->cleanup();
}
void EvalFunc::cleanup()
void EvalFunc::cleanup ()
{
for (auto& it : expr)
for (ExprEval::Expression* it : expr)
delete it;
for (auto& it : f)
for (ExprEval::FunctionList* it : f)
delete it;
for (auto& it : v)
for (ExprEval::ValueList* it : v)
delete it;
arg.clear();
delete gradient;
expr.clear();
f.clear();
v.clear();
arg.clear();
}
void EvalFunc::derivative (const std::string& function, const char* x)
{
if (!gradient)
gradient = new EvalFunc(function.c_str(),x);
}
Real EvalFunc::evaluate (const Real& x) const
{
Real result = Real(0);
size_t i = 0;
#ifdef USE_OPENMP
i = omp_get_thread_num();
#endif
if (i >= arg.size())
return 0;
Real result = Real(0);
return result;
try {
*arg[i] = x;
result = expr[i]->Evaluate();
@ -160,6 +170,16 @@ Real EvalFunc::evaluate (const Real& x) const
}
Real EvalFunc::deriv (Real x) const
{
if (gradient)
return gradient->evaluate(x);
// Evaluate derivative using central difference
return (this->evaluate(x+0.5*dx) - this->evaluate(x-0.5*dx)) / dx;
}
EvalFunction::EvalFunction (const char* function) : gradient{}, dgradient{}
{
try {
@ -178,10 +198,10 @@ EvalFunction::EvalFunction (const char* function) : gradient{}, dgradient{}
v[i] = new ExprEval::ValueList;
f[i]->AddDefaultFunctions();
v[i]->AddDefaultValues();
v[i]->Add("x",0,false);
v[i]->Add("y",0,false);
v[i]->Add("z",0,false);
v[i]->Add("t",0,false);
v[i]->Add("x",0.0,false);
v[i]->Add("y",0.0,false);
v[i]->Add("z",0.0,false);
v[i]->Add("t",0.0,false);
expr[i]->SetFunctionList(f[i]);
expr[i]->SetValueList(v[i]);
expr[i]->Parse(function);
@ -192,7 +212,7 @@ EvalFunction::EvalFunction (const char* function) : gradient{}, dgradient{}
}
}
catch (ExprEval::Exception e) {
cleanup();
this->cleanup();
ExprException(e,"parsing",function);
}
@ -205,26 +225,28 @@ EvalFunction::EvalFunction (const char* function) : gradient{}, dgradient{}
EvalFunction::~EvalFunction ()
{
cleanup();
this->cleanup();
}
void EvalFunction::cleanup()
void EvalFunction::cleanup ()
{
for (auto& it : expr)
for (ExprEval::Expression* it : expr)
delete it;
for (auto& it : f)
for (ExprEval::FunctionList* it : f)
delete it;
for (auto& it : v)
for (ExprEval::ValueList* it : v)
delete it;
for (auto& it : gradient)
for (EvalFunction* it : gradient)
delete it;
for (auto& it : dgradient)
for (EvalFunction* it : dgradient)
delete it;
arg.clear();
expr.clear();
f.clear();
v.clear();
arg.clear();
gradient.fill(nullptr);
dgradient.fill(nullptr);
}
@ -276,7 +298,7 @@ Real EvalFunction::evaluate (const Vec3& X) const
i = omp_get_thread_num();
#endif
if (i >= arg.size())
return 0;
return result;
*arg[i].x = X.x;
*arg[i].y = X.y;
@ -353,14 +375,14 @@ EvalFunctions::EvalFunctions (const std::string& functions,
const std::string& variables)
{
std::vector<std::string> components = splitComps(functions,variables);
for (const auto& comp : components)
for (const std::string& comp : components)
p.push_back(new EvalFunction(comp.c_str()));
}
EvalFunctions::~EvalFunctions ()
{
for (auto& it : p)
for (EvalFunction* it : p)
delete it;
}

35
src/Utility/ExprFunctions.h
View File

@ -42,23 +42,36 @@ class EvalFunc : public ScalarFunc
std::vector<Real*> arg; //!< Function argument values
EvalFunc* gradient; //!< First derivative expression
Real dx; //!< Domain increment for calculation of numerical derivative
public:
static int numError; //!< Error counter - set by the exception handler
//! \brief The constructor parses the expression string.
EvalFunc(const char* function, const char* x = "x" );
EvalFunc(const char* function, const char* x = "x", Real eps = Real(1.0e-8));
//! \brief The destructor frees the dynamically allocated objects.
virtual ~EvalFunc();
static int numError; //!< Error counter - set by the exception handler
//! \brief Adds an expression function for a first derivative.
void derivative(const std::string& function, const char* x = "x");
//! \brief Returns whether the function is time-independent or not.
virtual bool isConstant() const { return false; }
//! \brief Returns the first-derivative of the function.
virtual Real deriv(Real x) const;
protected:
//! \brief Non-implemented copy constructor to disallow copying.
EvalFunc(const EvalFunc&);
//! \brief Non-implemented assigment operator to disallow copying.
EvalFunc& operator=(const EvalFunc&);
EvalFunc(const EvalFunc&) = delete;
//! \brief Non-implemented assignment operator to disallow copying.
EvalFunc& operator=(const EvalFunc&) = delete;
//! \brief Evaluates the function expression.
virtual Real evaluate(const Real& x) const;
//! \brief Cleanup allocated data.
//! \brief Cleans up the allocated data.
void cleanup();
};
@ -108,14 +121,14 @@ public:
virtual Real dderiv(const Vec3& X, int dir1, int dir2) const;
protected:
//! \brief Non-implemented copy constructor to disallow copying.
EvalFunction(const EvalFunction&) = delete;
//! \brief Non-implemented assignment operator to disallow copying.
EvalFunction& operator=(const EvalFunction&) = delete;
//! \brief Evaluates the function expression.
virtual Real evaluate(const Vec3& X) const;
//! \brief Non-implemented copy constructor to disallow copying.
EvalFunction(const EvalFunction&);
//! \brief Non-implemented assignment operator to disallow copying.
EvalFunction& operator=(const EvalFunction&);
//! \brief Cleanup allocated data.
//! \brief Cleans up the allocated data.
void cleanup();
};

19
src/Utility/Function.h
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@ -117,8 +117,23 @@ namespace utl
}
//! \brief Scalar-valued unary function of a scalar value.
typedef utl::Function<Real,Real> ScalarFunc;
/*!
\brief Scalar-valued unary function of a scalar value.
*/
class ScalarFunc : public utl::Function<Real,Real>
{
protected:
//! \brief The constructor is protected to allow sub-class instances only.
ScalarFunc() {}
public:
//! \brief Empty destructor.
virtual ~ScalarFunc() {}
//! \brief Returns the first-derivative of the function.
virtual Real deriv(Real x) const { return Real(0); }
};
/*!

26
src/Utility/Functions.C
View File

@ -34,6 +34,12 @@ Real RampFunc::evaluate (const Real& x) const
}
Real RampFunc::deriv (Real x) const
{
return x < xmax ? fval/xmax : Real(0);
}
Real DiracFunc::evaluate (const Real& x) const
{
return fabs(x-xmax) < 1.0e-4 ? amp : Real(0);
@ -52,6 +58,12 @@ Real SineFunc::evaluate (const Real& x) const
}
Real SineFunc::deriv (Real x) const
{
return freq*scale*cos(freq*x+phase);
}
Real ConstTimeFunc::evaluate (const Vec3& X) const
{
const Vec4* Xt = dynamic_cast<const Vec4*>(&X);
@ -467,14 +479,21 @@ const ScalarFunc* utl::parseTimeFunction (const char* type, char* cline, Real C)
{
if (strncasecmp(type,"expr",4) == 0 && cline != nullptr)
{
cline = strtok(cline,":");
IFEM::cout << cline;
EvalFunc::numError = 0;
ScalarFunc* sf = new EvalFunc(cline,"t");
ScalarFunc* sf = new EvalFunc(cline,"t",C);
if (EvalFunc::numError > 0)
{
delete sf;
sf = nullptr;
}
// The derivative can be specified as a second expression after the colon
if ((cline = strtok(nullptr,":")))
{
IFEM::cout <<" (derivative: "<< cline <<")";
static_cast<EvalFunc*>(sf)->derivative(cline,"t");
}
return sf;
}
else if (strncasecmp(type,"Ramp",4) == 0 || strcmp(type,"Tinit") == 0)
@ -519,7 +538,8 @@ const ScalarFunc* utl::parseTimeFunction (const char* type, char* cline, Real C)
}
ScalarFunc* utl::parseTimeFunc (const char* func, const std::string& type)
ScalarFunc* utl::parseTimeFunc (const char* func, const std::string& type,
Real eps)
{
char* cstr = nullptr;
const ScalarFunc* sf = nullptr;
@ -527,7 +547,7 @@ ScalarFunc* utl::parseTimeFunc (const char* func, const std::string& type)
{
IFEM::cout <<"(expression) ";
if (func) cstr = strdup(func);
sf = parseTimeFunction("expression",cstr);
sf = parseTimeFunction("expression",cstr,eps);
}
else if (type == "linear")
sf = parseTimeFunction(func,cstr);

13
src/Utility/Functions.h
View File

@ -53,6 +53,9 @@ public:
//! \brief Returns whether the function is identically zero or not.
virtual bool isZero() const { return scale == Real(0); }
//! \brief Returns the first-derivative of the function.
virtual Real deriv(Real x) const { return scale; }
protected:
//! \brief Evaluates the function at \a x.
virtual Real evaluate(const Real& x) const { return scale*x; }
@ -75,6 +78,9 @@ public:
//! \brief Returns whether the function is identically zero or not.
virtual bool isZero() const { return fval == Real(0); }
//! \brief Returns the first-derivative of the function.
virtual Real deriv(Real x) const;
protected:
//! \brief Evaluates the function at \a x.
virtual Real evaluate(const Real& x) const;
@ -143,6 +149,9 @@ public:
//! \brief Returns whether the function is identically zero or not.
virtual bool isZero() const { return scale == Real(0); }
//! \brief Returns the first-derivative of the function.
virtual Real deriv(Real x) const;
protected:
//! \brief Evaluates the function at \a x.
virtual Real evaluate(const Real& x) const;
@ -540,8 +549,10 @@ namespace utl
//! \brief Creates a time function by parsing a character string.
//! \param[in] func Character string to parse function definition from
//! \param[in] type Function definition type flag
//! \param[in] eps Domain increment for calculation of numerical derivative
ScalarFunc* parseTimeFunc(const char* func,
const std::string& type = "expression");
const std::string& type = "expression",
Real eps = Real(1.0e-8));
//! \brief Creates a scalar-valued function by parsing a character string.
//! \param[in] func Character string to parse function definition from

42
src/Utility/Test/TestFunctions.C Normal file
View File

@ -0,0 +1,42 @@
//==============================================================================
//!
//! \file TestFunctions.C
//!
//! \date Apr 28 2018
//!
//! \author Knut Morten Okstad / SINTEF
//!
//! \brief Tests for parsing of functions.
//!
//==============================================================================
#include "Functions.h"
#include <cstdlib>
#include <cmath>
#include "gtest/gtest.h"
TEST(TestScalarFunc, ParseDerivative)
{
const char* func1 = "sin(1.5*t)*t";
const char* func2 = "sin(1.5*t)*t:1.5*cos(1.5*t)*t+sin(1.5*t)";
ScalarFunc* f1 = utl::parseTimeFunc(func1,"expression");
ScalarFunc* f2 = utl::parseTimeFunc(func2,"expression");
ASSERT_TRUE(f1 != nullptr);
ASSERT_TRUE(f2 != nullptr);
double t = 0.0;
for (int i = 0; i < 20; i++)
{
t += 0.314*(double)random()/(double)RAND_MAX;
std::cout <<"f("<< t <<") = "<< (*f1)(t)
<<" f'("<< t <<") = "<< f1->deriv(t) << std::endl;
EXPECT_FLOAT_EQ((*f1)(t),sin(1.5*t)*t);
EXPECT_FLOAT_EQ((*f2)(t),sin(1.5*t)*t);
EXPECT_FLOAT_EQ(f1->deriv(t),1.5*cos(1.5*t)*t+sin(1.5*t));
EXPECT_FLOAT_EQ(f2->deriv(t),1.5*cos(1.5*t)*t+sin(1.5*t));
}
}