trapInteg.c File Reference

Provides functions for performing trapezoidal integration on data sets. More...

#include "mdb.h"

Go to the source code of this file.

Functions
long	trapazoidIntegration (double *x, double *y, long n, double *integral)
	Computes the integral of a dataset using the trapezoidal rule.
long	trapazoidIntegration1 (double *x, double *y, long n, double *integral)
	Computes the integral as a function of x using the trapezoidal rule.

Detailed Description

Provides functions for performing trapezoidal integration on data sets.

Copyright

• (c) 2002 The University of Chicago, as Operator of Argonne National Laboratory.
• (c) 2002 The Regents of the University of California, as Operator of Los Alamos National Laboratory.

License

This file is distributed under the terms of the Software License Agreement found in the file LICENSE included with this distribution.

Author

M. Borland, R. Soliday

Definition in file trapInteg.c.

Function Documentation

trapazoidIntegration()

long trapazoidIntegration	(	double *	x,
		double *	y,
		long	n,
		double *	integral )

Computes the integral of a dataset using the trapezoidal rule.

This function calculates the integral of the given data points using the trapezoidal rule.

Parameters

x	Pointer to the array of x-values.
y	Pointer to the array of y-values.
n	The number of data points.
integral	Pointer to store the computed integral.

Returns

Returns 1 on success, 0 on failure.

Definition at line 29 of file trapInteg.c.

                                                                          {
  double sum;
  long i;
 
  if (!x || !y || !integral || n <= 1)
    return 0;
  sum = y[n - 1] * x[n - 1] - y[0] * x[0];
  for (i = 0; i < n - 1; i++)
    sum += y[i] * x[i + 1] - y[i + 1] * x[i];
  *integral = sum / 2;
  return 1;
}

trapazoidIntegration1()

long trapazoidIntegration1	(	double *	x,
		double *	y,
		long	n,
		double *	integral )

Computes the integral as a function of x using the trapezoidal rule.

This function calculates the integral at each x-value using the trapezoidal rule.

Parameters

x	Pointer to the array of x-values.
y	Pointer to the array of y-values.
n	The number of data points.
integral	Pointer to store the computed integral values.

Returns

Returns 1 on success, 0 on failure.

Definition at line 53 of file trapInteg.c.

                                                                           {
  long i;
 
  if (!x || !y || !integral || n <= 1)
    return 0;
  integral[0] = 0;
  for (i = 1; i < n; i++)
    integral[i] = integral[i - 1] + (y[i] + y[i - 1]) * (x[i] - x[i - 1]) / 2;
  return 1;
}