clog

Compute the base-e logarithm of a complex number.

Interface Definition

C interface:

float complex clogf(float complex x);

double complex clog(double complex x);

long double complex clogl(long double complex x);

Parameters

Parameter	Type	Description	Input/Output
x	For clogf, x is of complex single-precision floating-point type. For clog, x is of complex double-precision floating-point type. For clogl, x is of complex, long, double-precision floating-point type.	Floating-point value of the input data.	Input

Parameter

Type

Description

Input/Output

For clogf, x is of complex single-precision floating-point type.

For clog, x is of complex double-precision floating-point type.

For clogl, x is of complex, long, double-precision floating-point type.

Floating-point value of the input data.

Input

Return Value

The base-e 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	π/2
+0	-inf	inf	–π/2
+0	SNaN	NaN	NaN
+0	–SNaN	NaN	NaN
+0	QNaN	NaN	NaN
+0	–QNaN	NaN	NaN
-0	+0	-inf	π
-0	-0	-inf	–π
-0	inf	inf	π/2
-0	-inf	inf	–π/2
-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	π/4
inf	-inf	inf	–π/4
inf	SNaN	inf	NaN
inf	–SNaN	inf	NaN
inf	QNaN	inf	NaN
inf	–QNaN	inf	NaN
-inf	+0	inf	π
-inf	-0	inf	–π
-inf	inf	inf	3*π/4
-inf	-inf	inf	–3*π/4
-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

C interface:

    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 = clog(__builtin_complex(x1, y1));
    double complex z2 = clog(__builtin_complex(x2, y2));
    double complex z3 = clog(__builtin_complex(x3, y3));
    double complex z4 = clog(__builtin_complex(x4, y4));
    double complex z5 = clog(__builtin_complex(x5, y5));
    // print result
    printf("/*\n");
    printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x1, y1, __real__(z1), __imag__(z1));
    printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x2, y2, __real__(z2), __imag__(z2));
    printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x3, y3, __real__(z3), __imag__(z3));
    printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x4, y4, __real__(z4), __imag__(z4));
    printf(" * clog(%.2f + %.2f*I) = %.6f + %.6f*I\n", x5, y5, __real__(z5), __imag__(z5));
 
   /*
    * clog(inf + inf*I) = inf + 0.785398*I
    * clog(2.00 + 3.00*I) = 1.282475 + 0.982794*I
    * clog(-2.50 + -3.40*I) = 1.439880 + -2.204819*I
    * clog(nan + nan*I) = nan + nan*I
    * clog(0.00 + 0.00*I) = -inf + 0.000000*I
    **/

Parent topic: Function Syntax