mxIsInf (C and Fortran)

Determine whether input is infinite

C Syntax

#include "matrix.h"
bool mxIsInf(double value);

Fortran Syntax

#include "fintrf.h"
integer*4 mxIsInf(value)
real*8 value

Arguments

value

Double-precision, floating-point number to test

Returns

Logical 1 (true) if value is infinite, and logical 0 (false) otherwise.

Description

Call mxIsInf to determine whether value is equal to infinity or minus infinity. MATLAB^® software stores the value of infinity in a permanent variable named Inf, which represents IEEE^® arithmetic positive infinity. The value of the variable Inf is built into the system; you cannot modify it.

Operations that return infinity include:

• Division by 0. For example, 5/0 returns infinity.

• Operations resulting in overflow. For example, exp(10000) returns infinity because the result is too large to be represented on your machine.

If value equals NaN (Not-a-Number), then mxIsInf returns false. In other words, NaN is not equal to infinity.

Examples

See these examples in matlabroot/extern/examples/mx:

• mxisfinite.c