floatutil.c File Reference

Working with floats. More...

#include "tpcclibConfig.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <math.h>
#include "tpcextensions.h"

Go to the source code of this file.

Functions
int	floatMatch (const float v1, const float v2, const float lim)
int	floatMatchRel (const float v1, const float v2, const float lim)
float	floatMachEps ()
void	floatCopy (float *t, float *s, const unsigned int n)
unsigned int	floatMaxIndex (float *a, const unsigned int n)
float	floatSum (float *a, const unsigned int n)
float	floatMean (float *a, const unsigned int n)
int	floatGetWithUnit (const char *s, float *v, int *u)
int	floatSpanPositives (float *a, const int n)
int	floatCSpanPositives (float *a, const int n)
unsigned int	floatNonzeroes (float *a, const unsigned int n)

Detailed Description

Working with floats.

Author

Vesa Oikonen

Definition in file floatutil.c.

Function Documentation

floatCopy()

void floatCopy	(	float *	t,
		float *	s,
		const unsigned int	n )

Copy double values from the 2nd array to the first.

See also

doubleCopy

Parameters

t	Target array.
s	Source array.
n	Length of arrays.

Definition at line 94 of file floatutil.c.

  {
  unsigned int i;
  if(t==NULL || s==NULL || n<1) return;
  for(i=0; i<n; i++) t[i]=s[i];
}

floatCSpanPositives()

int floatCSpanPositives	(	float *	a,
		const int	n )

Returns the length of array consisting of non-positive (<=0 and NaN) values.

Returns

Returns the index of first positive value in the given array.

See also

doubleCSpanPositives, floatSpanPositives, atofList

Parameters

a	Pointer to the array.
n	Length of the array.

Definition at line 228 of file floatutil.c.

  {
  if(a==NULL || n<1) return(0);
  int i=0;
  for(i=0; i<n; i++) if(a[i]>0.0) break;
  return(i);
}

floatGetWithUnit()

int floatGetWithUnit	(	const char *	s,
		float *	v,
		int *	u )

Reads numerical value and its unit from argument string.

Both decimal point and comma are accepted. Optional result float value is set to NaN if string was not valid value. Optional unit is set to UNIT_UNKNOWN, if not valid or not found.

Returns

0 if numerical value successfully read, and 1 in case of an error.

See also

doubleGetWithUnit, atofVerified, atofCheck

Parameters

s	String from where float and unit is read; string must not contain any extra space characters.
v	Pointer to the float; enter NULL, if not needed.
u	Pointer to int for unit code; enter NULL, if not needed.

Definition at line 174 of file floatutil.c.

  {
  if(v!=NULL) *v=nanf(""); 
  if(u!=NULL) *u=UNIT_UNKNOWN; 
  if(s==NULL) return 1;
  int n=strTokenNr(s, " \t"); if(n==0 || n>2) return 1;
  if(n==1) { // no unit
    double dv;
    if(atofCheck(s, &dv)) return 1;
    *v=(float)dv; return 0;
  }
  /* separate number and unit */
  char buf[64];
  n=strTokenNCpy(s, " \t", 1, buf, 64);
  double dv;
  if(atofCheck(buf, &dv)) return 1;
  *v=(float)dv;
  if(u==NULL) return 0;
  n=strTokenNCpy(s, " \t", 2, buf, 64);
  *u=unitIdentify(buf);
  return 0;
}

floatMachEps()

float floatMachEps

(

)

Estimates the machine epsilon, the upper bound on the relative error due to rounding in floating point arithmetic, within one order of magnitude of the true machine epsilon.

Standard C library should also have FLT_EPSILON and DBL_EPSILON in float.h.

Returns

Estimate of machine epsilon.

Author

Vesa Oikonen

See also

doubleMachEps, floatMatchRel, floatMatch

Definition at line 82 of file floatutil.c.

{
  float macheps=1.0;
  do {macheps/=2.0;} while((1.0+macheps/2.0)!=1.0);
  return(macheps);
}

floatMatch()

int floatMatch	(	const float	v1,
		const float	v2,
		const float	lim )

Verifies that given two floats have the same value inside given limits. Values are considered to match also if both are NaNs.

Returns

1 if match is found, and 0 if not.

Author

Vesa Oikonen

See also

doubleMatch, floatMatchRel, floatMachEps, atofCheck

Parameters

v1	First value
v2	Second value
lim	Limit for absolute difference (if <0 then test will fail every time)

Definition at line 27 of file floatutil.c.

  {
  if(isnan(v1) && isnan(v2)) return 1;
  if(isnan(v1) || isnan(v2)) return 0;
  if(v1==v2) return 1;
  if(isnan(lim) || lim<0.0) return 0;
  if(fabsf(v1-v2)<=lim) return 1;
  return 0;
}

Referenced by imgCompareConc(), imgCompareTimes(), and imgReadDICOM().

floatMatchRel()

int floatMatchRel	(	const float	v1,
		const float	v2,
		const float	lim )

Verifies that given two floats have the same value inside given relative limit |2*(v1-v2)/(v1+v2)|.

Values are considered to match also if both are NaNs, but not if mean is zero (unless both are exactly zero).

Returns

1 if match is found, and 0 if not.

Author

Vesa Oikonen

See also

doubleMatchRel, floatMatch, floatMachEps

Parameters

v1	First value.
v2	Second value.
lim	Limit for relative difference (if <0 then test will fail every time).

Definition at line 54 of file floatutil.c.

  {
  if(isnan(v1) && isnan(v2)) return 1;
  if(isnan(v1) || isnan(v2)) return 0;
  if(v1==v2) return 1;
  if(isnan(lim)) return 0;
  float mean;
  mean=0.5*(v1+v2); if(!isnormal(mean)) return 0;
  if(fabsf((v1-v2)/mean)<=lim) return 1;
  return 0;
}

Referenced by imgCompareConc(), and imgCompareTimes().

floatMaxIndex()

unsigned int floatMaxIndex	(	float *	a,
		const unsigned int	n )

Find the maximum value in given float array.

Returns

The index [0..n-1] of maximum value in array; 0 is returned also in case of errors.

See also

doubleMaxIndex, floatSpanPositives, floatCSpanPositives

Parameters

a	Pointer to float array.
n	Length of array.

Definition at line 113 of file floatutil.c.

  {
  if(a==NULL || n<1) return(0);
  unsigned int i, mi=0;
  float mv=nanf("");
  for(i=0; i<n; i++) if(isnan(mv) || a[i]>mv) {mv=a[i]; mi=i;}
  return(mi);
}

floatMean()

float floatMean	(	float *	a,
		const unsigned int	n )

Calculate the mean of values in given float array.

Returns

The mean of array values, or NaN in case of an error.

See also

doubleMean, floatSum, floatMaxIndex, fstatMeanSD

Parameters

a	Pointer to float array.
n	Length of array.

Definition at line 150 of file floatutil.c.

  {
  if(a==NULL || n<1) return(nanf(""));
  float s=0.0;
  unsigned int i, ci=0;
  for(i=0; i<n; i++) if(!isnan(a[i])) {ci++; s+=a[i];}
  if(ci<1) return(nanf(""));
  return(s/(float)ci);
}

floatNonzeroes()

unsigned int floatNonzeroes	(	float *	a,
		const unsigned int	n )

Find the number of non-zero values in given float array. Negative values are counted, but NaNs are not.

Returns

The number of non-zero values in array; 0 is returned also in case of errors.

See also

doubleNonzeroes, floatSpanPositives

Parameters

a	Pointer to float array.
n	Length of array.

Definition at line 247 of file floatutil.c.

  {
  if(a==NULL || n<1) return(0);
  unsigned int i, m=0;
  for(i=0; i<n; i++) if(fabsf(a[i])>0.0) m++;
  return(m);
}

Referenced by imgContents().

floatSpanPositives()

int floatSpanPositives	(	float *	a,
		const int	n )

Returns the length of array consisting of only positive (>0 and not NaN) values.

Returns

Returns the index of first nonpositive value in the given array.

See also

doubleSpanPositives, floatCSpanPositives, atofList, floatNonzeroes

Parameters

a	Pointer to the array.
n	Length of the array.

Definition at line 210 of file floatutil.c.

  {
  if(a==NULL || n<1) return(0);
  int i=0;
  for(i=0; i<n; i++) if(!(a[i]>0.0)) break;
  return(i);
}

floatSum()

float floatSum	(	float *	a,
		const unsigned int	n )

Calculate the sum of values in given float array.

Returns

The sum of array values.

See also

doubleSum, floatMean, floatMaxIndex

Parameters

a	Pointer to float array.
n	Length of array.

Definition at line 132 of file floatutil.c.

  {
  float s=0.0;
  if(a==NULL || n<1) return(s);
  for(unsigned int i=0; i<n; i++) if(!isnan(a[i])) s+=a[i];
  return(s);
}