acosd

Compute the angle corresponding to the arccosine of the input real number.

Interface Definition

C interface:

float acosdf(float x);

double acosd(double x);

long double acosdl(long double x);

Parameters

Parameter	Type	Description	Input/Output
x	For acosdf, x is of single-precision floating-point type. For acosd, x is of double-precision floating-point type. For acosdl, x is of long double-precision floating-point type.	Floating-point value of the input data.	Input

Return Value

The angle y corresponding to the arccosine of the input x is returned, that is, y = acos(x) * 180/π. y ∈ [0, 180]
If the input is +0, the return value is 90.
If the input is -0, the return value is 90.
If the input x is 1, the return value is +0.
If the input x is -1, the return value is 180.
If the input |x| is greater than 1, the return value is NaN.
If the input is ±∞, the return value is NaN.
If the input is NaN, the return value is NaN.

Dependency

C: "km.h"

Example

C interface:

    // typical usage
    float x1 = -1.0, x2 = 1.0, x3 = 0.5, x4 = -0.5;
    float a = 0.0, b = INFINITY, c = -INFINITY, d = NAN;
    // print result
    printf("acosdf(1.0) = %.15f\n", acosdf(x1));
    printf("acosdf(-1.0) = %.15f\n", acosdf(x2));
    printf("acosdf(0.5) = %.15f\n", acosdf(x3));
    printf("acosdf(-0.5) = %.15f\n", acosdf(x4));
    printf("acosdf(0.0) = %.15f\n", acosdf(a));
    printf("acosdf(-0.0) = %.15f\n", acosdf(-a));
    printf("acosdf(INFINITY) = %.15f\n", acosdf(b));
    printf("acosdf(-INFINITY) = %.15f\n", acosdf(c));
    printf("acosdf(NAN) = %.15f\n", acosdf(d));
    /* 
     * acosdf(1.0) = 180.000000000000000
     * acosdf(-1.0) = 0.000000000000000
     * acosdf(0.5) = 60.000000000000000
     * acosdf(-0.5) = 120.000000000000000
     * acosdf(0.0) = 90.000000000000000
     * acosdf(-0.0) = 90.000000000000000
     * acosdf(INFINITY) = nan
     * acosdf(-INFINITY) = nan
     * acosdf(NAN) = nan
     * 
     * */

Parent topic: Trigonometric Functions