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/*
FUNCTION
<<clog10>>, <<clog10f>>---complex base-10 logarithm
INDEX
clog10
INDEX
clog10f
SYNOPSIS
#define _GNU_SOURCE
#include <complex.h>
double complex clog10(double complex <[z]>);
float complex clog10f(float complex <[z]>);
DESCRIPTION
These functions compute the complex base-10 logarithm of <[z]>.
<<clog10>> is equivalent to <<clog>>(<[z]>)/<<log>>(10).
<<clog10f>> is identical to <<clog10>>, except that it performs
its calculations on <<floats complex>>.
RETURNS
The clog10 functions return the complex base-10 logarithm value.
PORTABILITY
<<clog10>> and <<clog10f>> are GNU extensions.
*/
#include <complex.h>
#include <math.h>
double complex
clog10(double complex z)
{
double complex w;
double p, rr;
rr = cabs(z);
p = log10(rr);
rr = atan2(cimag(z), creal(z)) * M_IVLN10;
w = p + rr * I;
return w;
}
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