clog2
Compute the base-2 logarithm of a complex number.
Interface Definition
C interface:
float complex clog2f(float complex x);
double complex clog2(double complex x);
Parameters
Parameter |
Type |
Description |
Input/Output |
|---|---|---|---|
x |
|
Floating-point value of the input data. |
Input |
Return Value
- The base-2 logarithm y of x is returned.
- The special values are listed in the following table.
Real Part of the Input (x.real)
Imaginary Part of the Input (x.imag)
Real Part of the Output (y.real)
Imaginary Part of the Output (y.imag)
+0
+0
-inf
+0
+0
-0
-inf
-0
+0
inf
inf
0x40022123045b5dec(pi/2ln2)
+0
-inf
inf
0xc0022123045b5dec(-pi/2ln2)
+0
SNaN
NaN
NaN
+0
–SNaN
NaN
NaN
+0
QNaN
NaN
NaN
+0
–QNaN
NaN
NaN
-0
+0
-inf
0x40122123045b5dec(pi/ln2)
-0
-0
-inf
0xc0122123045b5dec(-pi/ln2)
-0
inf
inf
0x40022123045b5dec(pi/2ln2)
-0
-inf
inf
0xc0022123045b5dec(-pi/2ln2)
-0
SNaN
NaN
NaN
-0
–SNaN
NaN
NaN
-0
QNaN
NaN
NaN
-0
–QNaN
NaN
NaN
inf
+0
inf
+0
inf
-0
inf
-0
inf
inf
inf
0x3ff22123045b5dec(pi/4ln2)
inf
-inf
inf
0xbff22123045b5dec(-pi/4ln2)
inf
SNaN
inf
NaN
inf
–SNaN
inf
NaN
inf
QNaN
inf
NaN
inf
–QNaN
inf
NaN
-inf
+0
inf
0x40122123045b5dec(pi/ln2)
-inf
-0
inf
0xc0122123045b5dec(-pi/ln2)
-inf
inf
inf
0x400b31b486890ce1(3*pi/4ln2)
-inf
-inf
inf
0xc00b31b486890ce1(-3*pi/4ln2)
-inf
SNaN
inf
NaN
-inf
–SNaN
inf
NaN
-inf
QNaN
inf
NaN
-inf
–QNaN
inf
NaN
SNaN
+0
NaN
NaN
SNaN
-0
NaN
NaN
SNaN
inf
inf
NaN
SNaN
-inf
inf
NaN
SNaN
SNaN
NaN
NaN
SNaN
–SNaN
NaN
NaN
SNaN
QNaN
NaN
NaN
SNaN
–QNaN
NaN
NaN
–SNaN
+0
NaN
NaN
–SNaN
-0
NaN
NaN
–SNaN
inf
inf
NaN
–SNaN
-inf
inf
NaN
–SNaN
SNaN
NaN
NaN
–SNaN
–SNaN
NaN
NaN
–SNaN
QNaN
NaN
NaN
–SNaN
–QNaN
NaN
NaN
QNaN
+0
NaN
NaN
QNaN
-0
NaN
NaN
QNaN
inf
inf
NaN
QNaN
-inf
inf
NaN
QNaN
SNaN
NaN
NaN
QNaN
–SNaN
NaN
NaN
QNaN
QNaN
NaN
NaN
QNaN
–QNaN
NaN
NaN
–QNaN
+0
NaN
NaN
–QNaN
-0
NaN
NaN
–QNaN
inf
inf
NaN
–QNaN
-inf
inf
NaN
–QNaN
SNaN
NaN
NaN
–QNaN
–SNaN
NaN
NaN
–QNaN
QNaN
NaN
NaN
–QNaN
–QNaN
NaN
NaN
Dependency
C: "kc.h"
Example
// typical usage
double x1 = INFINITY, y1 = INFINITY;
double x2 = 2.0, y2 = 3.0;
double x3 = -2.5, y3 = -3.4;
double x4 = NAN, y4 = NAN;
double x5 = 0, y5 = 0;
double complex z1 = clog2(__builtin_complex(x1, y1));
double complex z2 = clog2(__builtin_complex(x2, y2));
double complex z3 = clog2(__builtin_complex(x3, y3));
double complex z4 = clog2(__builtin_complex(x4, y4));
double complex z5 = clog2(__builtin_complex(x5, y5));
// print result
printf("/*\n");
printf(" * clog2(%.2f + %.2f*I) = %.6f + %.6f*I\n", x1, y1, __real__(z1), __imag__(z1));
printf(" * clog2(%.2f + %.2f*I) = %.6f + %.6f*I\n", x2, y2, __real__(z2), __imag__(z2));
printf(" * clog2(%.2f + %.2f*I) = %.6f + %.6f*I\n", x3, y3, __real__(z3), __imag__(z3));
printf(" * clog2(%.2f + %.2f*I) = %.6f + %.6f*I\n", x4, y4, __real__(z4), __imag__(z4));
printf(" * clog2(%.2f + %.2f*I) = %.6f + %.6f*I\n", x5, y5, __real__(z5), __imag__(z5));
printf(" **/\n");
/*
* clog2(inf + inf*I) = inf + 1.133090*I
* clog2(2.00 + 3.00*I) = 1.850220 + 1.417872*I
* clog2(-2.50 + -3.40*I) = 2.077308 + -3.180882*I
* clog2(nan + nan*I) = nan + nan*I
* clog2(0.00 + 0.00*I) = -inf + 0.000000*I
**/