cabs, cabsl

raw OCR

Calculates the absolute value of complex number.

Defined in header <math.h>

Syntax

#include <math.h>
double cabs(struct complex z);
long double cabsKstruct  complexl z);

Portability

	DOS	UNIX	Windows	ANSI C	C++ only
cabs	■	■	■	■
cabsl	■		■

Remarks

cabs is a macro that calculates the absolute value of z, a complex number, z is a structure with type complex; the structure is defined in math.h as

struct complex { double X,.y; };

where x is the real part, and y is the imaginary part.

Calling cabs is equivalent to calling sqrt with the real and imaginary components of z as shown here:

sqrt(z.x * z.x + z.y * z.y) cabsl is the long double version; it takes a a structure with type joomplexl as an argument, and returns a long double result. The structure is defined in math.h as

struct _complexl { long double x, y; }; If you are using C++, use the complex type defined in complex.h, and the function abs.

Return value

cabs (or cabsl) returns the absolute value of z, a double. On overflow,

cabs (or cabsl) returns HUGE_VAL	(or _LHUGE_VAL)	and sets the

global variable errno to ERANGE Result out of range

Error handling for these functions can be modified through the functions matherr and _matherrl.

Example

#include <stdio.h>
#include <math.h>
lifdef   cplusplus
   #include <complex.h>
lendif
#ifdef   cplusplus /* if C++, use  class complex */
void print_abs (void)
{
   complex z (1.0, 2.0);
   double  absval;

   absval = abs (z);
   printfC'The absolute value of  %.21fi %.21f] is %.21f",
           real(z), imag(z), absval);
}
telse  /* Function below is  for C (and not C++). */
void print_abs (void)
{
   struct complex z;
   double absval;

   z.x = 2.0;
   z.y = 1.0;
   absval = cabs(z);

   printfC'The absolute value of  %.21fi l.21fj is %.21f",
           z.x, z.y, absval);
}
#endif

int main (void)
{
   print_abs ();
   return 0;

Differences from modern implementations

Nothing recorded yet.

Modern references

These are search links, not yet checked by hand.

Stable link: /3.1/math.h/cabs/ · short form /3.1/cabs/