tgamma

Return the gamma value of the input parameter x, that is, $\text{[math]}$ .

Interface Definition

C interface:

float tgammaf(float x);

float tgammaf_18(float x);double tgamma(double x);

double tgamma(double x);

tgammaf_18 is provided only in the high-precision version.

Parameters

Parameter	Type	Description	Input/Output
x	For tgammaf and tgammaf_18, x is of single-precision floating-point type. For tgamma, x is of double-precision floating-point type.	Floating-point value of the input data.	Input

Return Value

The gamma value y of x is returned. y ∈ (-INF, +INF)
If the input x is ±0, the return value is ±INF.
If the input x is a negative integer, the return value is -NaN.
If the input x is NaN, the return value is NaN.
If the input x is +INF, the return value is +INF.
If the input x is -INF, the return value is -NAN.

Dependencies

C: "km.h"

Examples

C interface:

 // typical usage 
    float x1 = -2.5, x2 = -1.5, x3 = 1.5, x4 = 2.5; 
    // special handling 
    float a = -2.0, b = -0.0, c = INFINITY, d = NAN; 
    // print result 
        printf("tgammaf(-2.5) = %.15f\n", tgammaf(x1)); 
        printf("tgammaf(-1.5) = %.15f\n", tgammaf(x2)); 
        printf("tgammaf(1.5) = %.15f\n", tgammaf(x3)); 
        printf("tgammaf(2.5) = %.15f\n", tgammaf(x4)); 
        printf("tgammaf(-2.0) = %.15f\n", tgammaf(a)); 
        printf("tgammaf(-0.0) = %.15f\n", tgammaf(b)); 
        printf("tgammaf(INFINITY) = %.15f\n", tgammaf(c)); 
        printf("tgammaf(NAN) = %.15f\n", tgammaf(d)); 
    /* 
     *  
     *  tgammaf(-2.5) = -0.945308744907379
     *  tgammaf(-1.5) = 2.363271713256836
     *  tgammaf(1.5) = 0.886226952075958
     *  tgammaf(2.5) = 1.329340338706970
     *  tgammaf(-2.0) = -nan
     *  tgammaf(-0.0) = -inf
     *  tgammaf(INFINITY) = inf
     *  tgammaf(NAN) = nan
     *
     * */

Parent topic: Special Functions