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Functions That Should Not Be Called with Complex Values

`atan2()`	`erf()`	`fdim()`	`fmin()`	`ilogb()`	`llround()`	`logb()`	`nextafter()`	`rint()`	`tgamma()`
`cbrt()`	`erfc()`	`floor()`	`fmod()`	`ldexp()`	`log10()`	`lrint()`	`nexttoward()`	`round()`	`trunc()`
`ceil()`	`exp2()`	`fma()`	`frexp()`	`lgamma()`	`log1p()`	`lround()`	`remainder()`	`scalbn()`
`copysign()`	`expm1()`	`fmax()`	`hypot()`	`llrint()`	`log2()`	`nearbyint()`	`remquo()`	`scalbln()`

This noncompliant code example attempts to take the base-2 logarithm of a complex number, resulting in undefined behavior:

Code Block

bgColor	#ffcccc
lang	c

#include <complex.h>
#include <tgmath.h>
 
void func(void) {
  double complex c = 2.0 + 4.0 * I;
  double complex result = log2(c);
}

...

If the clog2() function is not available for your implementation as an extension, you can take the base-2 logarithm of a complex number using log() instead of log2(), as log() can be used on complex arguments, as shown in this compliant solution:

Code Block

bgColor	#ccccff
lang	c

#include <complex.h>
#include <tgmath.h>
 
void func(void) {
  double complex c = 2.0 + 4.0 * I;
  double complex result = log(c)/log(2);
}

...

Code Block

bgColor	#ccccff
lang	c

#include <complex.h>
#include <tgmath.h>
 
void func(void) {
  double complex c = 2.0 + 4.0 * I;
  double complex result = log2(creal(c));
}

...

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