# dlaisnan.f man page

dlaisnan.f —

## Synopsis

### Functions/Subroutines

LOGICAL functiondlaisnan(DIN1, DIN2)DLAISNANtests input for NaN by comparing two arguments for inequality.

## Function/Subroutine Documentation

### LOGICAL function dlaisnan (double precisionDIN1, double precisionDIN2)

**DLAISNAN** tests input for NaN by comparing two arguments for inequality.

**Purpose:**

```
This routine is not for general use. It exists solely to avoid
over-optimization in DISNAN.
DLAISNAN checks for NaNs by comparing its two arguments for
inequality. NaN is the only floating-point value where NaN != NaN
returns .TRUE. To check for NaNs, pass the same variable as both
arguments.
A compiler must assume that the two arguments are
not the same variable, and the test will not be optimized away.
Interprocedural or whole-program optimization may delete this
test. The ISNAN functions will be replaced by the correct
Fortran 03 intrinsic once the intrinsic is widely available.
```

**Parameters:**

*DIN1*

`DIN1 is DOUBLE PRECISION`

*DIN2*

```
DIN2 is DOUBLE PRECISION
Two numbers to compare for inequality.
```

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

September 2012

Definition at line 75 of file dlaisnan.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

dlaisnan(3) is an alias of dlaisnan.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK