annuity

Compute the present value interest factor of an annuity. The input parameter is a real number.

Interface Definition

C interface:

float annuityf(float x, float y);

double annuity(double x, double y);

Parameters

Parameter	Type	Description	Input/Output
x	For annuityf, x is of single-precision floating-point type. For annuity, x is of double-precision floating-point type.	Floating-point value of the input data.	Input
y	For annuityf, y is of single-precision floating-point type. For annuity, y is of double-precision floating-point type.	Floating-point value of the input data.	Input

Return Value

If x is greater than –1 and y ∈ (–∞, +∞), the computing result is returned.
If x is any value and y is ±0, the return value is 0.
If x is NaN and y is any value, the return value is NaN.
If x is any value and y is NaN, the return value is NaN.
If x is +∞ and y is –1, the return value is –1. If y < –1, the return value is –∞. If y ∈ (–1, 0), the return value is –0.
If x = 0 and y != 0, the return value is y.
If x is –1 and y < 0, the return value is –1. If y > 0, the return value is +∞.
If x < –1 and y != 0, the return value is NaN.
If y is –∞ and x ∈ (–1, 0), the return value is 1.0/x. If x > 0, the return value is –∞.
If y is +∞ and x ∈ (–1, 0), the return value is +∞. If x > 0, the return value is 1.0/x.

Dependency

C: "km.h"

Example

C interface:

    // print result
    printf("annuity(1.0, 10.0) = %.15f\n", annuity(1.0, 10.0));
    printf("annuity(0.5, -3.0) = %.15f\n", annuity(0.5, -3.0));
    printf("annuity(0.3, -10.0) = %.15f\n", annuity(1.0, 10.0));
    printf("annuity(4, 2.0) = %.15f\n", annuity(0.5, -3.0));
    printf("annuity(INFINITY, 0) = %.15f\n", annuity(INFINITY, 0));
    printf("annuity(INFINITY, 0) = %.15f\n", annuity(INFINITY, 0));
    printf("annuity(1.0, NAN) = %.15f\n", annuity(1.0, NAN));
    printf("annuity(NAN, 1.0) = %.15f\n", annuity(NAN, 1.0));
    printf("annuity(INFINITY, -1.0) = %.15f\n", annuity(INFINITY, -1.0));
    printf("annuity(INFINITY, -10.0) = %.15f\n", annuity(INFINITY, -10.0));
    printf("annuity(INFINITY, 10.0) = %.15f\n", annuity(INFINITY, 10.0));
    printf("annuity(0, 1.0) = %.15f\n", annuity(0, 1.0));
    printf("annuity(-1.0, -1.0) = %.15f\n", annuity(-1.0, -1.0));
    printf("annuity(-1.0, 1.0) = %.15f\n", annuity(-1.0, 1.0));
    printf("annuity(-10.0, 1.0) = %.15f\n", annuity(-10.0, 1.0));
    printf("annuity(-0.5, -INFINITY) = %.15f\n", annuity(-0.5, -INFINITY));
    printf("annuity(0.5, -INFINITY) = %.15f\n", annuity(0.5, -INFINITY));
    printf("annuity(-0.5, INFINITY) = %.15f\n", annuity(-0.5, INFINITY));
    printf("annuity(0.5, INFINITY) = %.15f\n", annuity(0.5, INFINITY));
    /* 
     * annuity(1.0, 10.0) = 0.999023437500000
     * annuity(0.5, -3.0) = -4.750000000000000
     * annuity(0.3, -10.0) = 0.999023437500000
     * annuity(4, 2.0) = -4.750000000000000
     * annuity(INFINITY, 0) = 0.000000000000000
     * annuity(INFINITY, 0) = 0.000000000000000
     * annuity(1.0, NAN) = nan
     * annuity(NAN, 1.0) = nan
     * annuity(INFINITY, -1.0) = -1.000000000000000
     * annuity(INFINITY, -10.0) = -inf
     * annuity(INFINITY, 10.0) = 0.000000000000000
     * annuity(0, 1.0) = 1.000000000000000
     * annuity(-1.0, -1.0) = -1.000000000000000
     * annuity(-1.0, 1.0) = inf
     * annuity(-10.0, 1.0) = nan
     * annuity(-0.5, -INFINITY) = -2.000000000000000
     * annuity(0.5, -INFINITY) = -inf
     * annuity(-0.5, INFINITY) = inf
     * annuity(0.5, INFINITY) = 2.000000000000000
     * 
     * */

Parent topic: Special Functions