Trapeze Class Reference

#include <integration.h>

Inheritance diagram for Trapeze:

Collaboration diagram for Trapeze:

Public Member Functions
virtual double	operator() ()
double	operator() (double min, double max, double precision=1.0e-7, int max_iter=20)
	Trapeze (doubleFunction &f, double &Var, double min, double max, double precision=1.0e-7, int max_iter=20)
double	Trap (int n)
Public Member Functions inherited from doubleFunction
virtual	~doubleFunction ()

Detailed Description

Fast integration routine.

Interpolations are made with lines.

Example of use.

1) Define function to NumericalIntegration as class:

// Actual function to be NumericalIntegration
class Func1: public doubleFunction
{
// This should be in testinteg
public:
    double x;
    double cte1, cte2;
    // overloads pure virtual
    virtual double operator()()
    {
        return sqrt(1 + cte1 * cte1 * sin(cte2 * x) * sin(cte2 * x));
    }
};

2) In the main code

#include <data/integration.h>

Func1 cosine; // cosine surface
cosine.cte1 = fabs(cteA * cteA * cteB * cteB * vx * vx);
cosine.cte2 = fabs(cteB * vx);

Trapeze Trap(cosine, cosine.x, inte_low, inte_high);
integralt = Trap();

Definition at line 96 of file integration.h.

Constructor & Destructor Documentation

Trapeze()

Trapeze::Trapeze ( doubleFunction &  f, double &  Var, double  min, double  max, double  precision = 1.0e-7, int  max_iter = 20  )

inline

Constructor.

Parameter: f Pointer to function to be integrated Parameter: var Integration variable Parameter: min Integration lower limit Parameter: max Integration upper limit Parameter: precision Maximum error allowed Parameter: max_iter Maximum number of iterations

Definition at line 135 of file integration.h.

                                                          : func(f), x(Var)
    {
        a = min;
        b = max;
        EPS = precision;
        JMAX = max_iter;
    }

Member Function Documentation

operator()() [1/2]

double Trapeze::operator() ( )

virtual

Implements doubleFunction.

Definition at line 70 of file integration.cpp.

{   //adapted from qtrap
    double s_internal;
    double olds;
    int j;
    olds = -1.0e30;
    for (j = 1;j <= JMAX;j++)
    {
        s_internal = Trap(j);    //changed; Trap is integrating fcn
        if (fabs(s_internal - olds) <= EPS*fabs(olds))
            return s_internal;
        if (s_internal == 0.0 && olds == 0.0 && j > 6)
            return s_internal;
        olds = s_internal;
    }
    REPORT_ERROR(ERR_NUMERICAL,"Too many steps in routine qtrap_y\n");
}

operator()() [2/2]

double Trapeze::operator() ( double  min, double  max, double  precision = 1.0e-7, int  max_iter = 20  )

inline

With parameters. Parameter: min Integration lower limit Parameter: max Integration upper limit Parameter: precision Maximum error allowed Parameter: max_iter Maximum number of iterations

Definition at line 116 of file integration.h.

    {
        a = min;
        b = max;
        EPS = precision;
        JMAX = max_iter;
        return (*this)();
    }

Trap()

double Trapeze::Trap

(

int

n

)

Workhorse that doublely does the integral.

Definition at line 89 of file integration.cpp.

{ //adapted from trapzd
    double tnm;
    double sum;
    double del;
    int j;
    int it;
    if (n == 1)
    {
        it = 1;
        x = a;
        s = func();  //changed
        x = b;
        s += func(); //changed
        return (s *= 0.5 * (b - a));
    }
    else
    {
        for (it = 1, j = 1;j < n - 1;j++)
            it <<= 1;
        tnm = it;
        del = (b - a) / tnm;
        x = a + 0.5 * del;
        for (sum = 0.0, j = 1;j <= it;j++, x += del)
            sum += func(); //changed
        s = 0.5 * (s + (b - a) * sum / tnm);
        return s;
    }
}

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

• xmipp/libraries/data/integration.h
• xmipp/libraries/data/integration.cpp