fdim, fdimf, fdiml - cppreference.com (original) (raw)

Defined in header <math.h>
float fdimf( float x, float y ); (1) (since C99)
double fdim( double x, double y ); (2) (since C99)
long double fdiml( long double x, long double y ); (3) (since C99)
Defined in header <tgmath.h>
#define fdim( x, y ) (4) (since C99)

1-3) Returns the positive difference between x and y, that is, if x>y, returns x-y, otherwise (if x≤y), returns +0.

  1. Type-generic macro: If any argument has type long double, fdiml is called. Otherwise, if any argument has integer type or has type double, fdim is called. Otherwise, fdimf is called.

Contents

[edit] Parameters

x, y - floating-point value

[edit] Return value

If successful, returns the positive difference between x and y.

If a range error due to overflow occurs, +HUGE_VAL, +HUGE_VALF, or +HUGE_VALL is returned.

If a range error due to underflow occurs, the correct value (after rounding) is returned.

[edit] Error handling

Errors are reported as specified in Template:rllpt.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),

[edit] Notes

Equivalent to fmax(x-y, 0) except for the NaN handling requirements.

[edit] Example

#include <errno.h> #include <fenv.h> #include <math.h> #include <stdio.h> // #pragma STDC FENV_ACCESS ON   int main(void) { printf("fdim(4, 1) = %f, fdim(1, 4)=%f\n", fdim(4,1), fdim(1,4)); printf("fdim(4,-1) = %f, fdim(1,-4)=%f\n", fdim(4,-1), fdim(1,-4)); //error handling errno = 0; feclearexcept(FE_ALL_EXCEPT); printf("fdim(1e308, -1e308) = %f\n", fdim(1e308, -1e308)); if (errno == ERANGE) perror(" errno == ERANGE"); if (fetestexcept(FE_OVERFLOW)) puts(" FE_OVERFLOW raised"); }

Possible output:

fdim(4, 1) = 3.000000, fdim(1, 4)=0.000000 fdim(4,-1) = 5.000000, fdim(1,-4)=5.000000 fdim(1e308, -1e308) = inf errno == ERANGE: Numerical result out of range FE_OVERFLOW raised

[edit] References

[edit] See also