lib/correlate.c File Reference

#include "common.h"
#include "correlate.h"

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Functions
correlate *	correlateNew ()
void	correlateFree (struct correlate **pC)
void	correlateNext (struct correlate *c, double x, double y)
double	correlateResult (struct correlate *c)
double	correlateArrays (double *x, double *y, int size)

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Function Documentation

double correlateArrays	(	double *	x,
		double *	y,
		int	size
	)

Definition at line 49 of file correlate.c.

References correlateFree(), correlateNew(), correlateNext(), and correlateResult().

{
struct correlate *c = correlateNew();
double r;
int i;
for (i=0; i<size; ++i)
     correlateNext(c, x[i], y[i]);
r = correlateResult(c);
correlateFree(&c);
return r;
}

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void correlateFree

(

struct correlate **

pC

)

Definition at line 16 of file correlate.c.

References freez().

Referenced by correlateArrays().

{
freez(pC);
}

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struct correlate* correlateNew

(

)

[read]

Definition at line 9 of file correlate.c.

References AllocVar.

Referenced by correlateArrays().

{
struct correlate *c;
return AllocVar(c);
}

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void correlateNext	(	struct correlate *	c,
		double	x,
		double	y
	)

Definition at line 22 of file correlate.c.

References correlate::n, correlate::sumX, correlate::sumXX, correlate::sumXY, correlate::sumY, and correlate::sumYY.

Referenced by correlateArrays().

{
c->sumX += x;
c->sumXX += x*x;
c->sumXY += x*y;
c->sumY += y;
c->sumYY += y*y;
c->n += 1; 
}

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double correlateResult

(

struct correlate *

c

)

Definition at line 33 of file correlate.c.

References correlate::n, correlate::sumX, correlate::sumXX, correlate::sumXY, correlate::sumY, and correlate::sumYY.

Referenced by correlateArrays().

{
double r = 0;
if (c->n > 0)
    {
    double sp = c->sumXY - c->sumX*c->sumY/c->n;
    double ssx = c->sumXX - c->sumX*c->sumX/c->n;
    double ssy = c->sumYY - c->sumY*c->sumY/c->n;
    double q = ssx*ssy;
    if (q != 0)
        r = sp/sqrt(q);
    }
return r;
}

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