.TH SLAISNAN 1 "November 2006" " LAPACK auxiliary routine (version 3.1) " " LAPACK auxiliary routine (version 3.1) "
.SH NAME
SLAISNAN - i not for general use
.SH SYNOPSIS
.TP 17
LOGICAL FUNCTION
SLAISNAN(SIN1,SIN2)
.TP 17
.ti +4
REAL
SIN1,SIN2
.SH PURPOSE
This routine is not for general use. It exists solely to avoid
over-optimization in SISNAN.
.br
SLAISNAN 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.
.br
Strictly speaking, Fortran does not allow aliasing of function
arguments. So 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.
.SH ARGUMENTS
.TP 9
SIN1 (input) REAL
SIN2 (input) REAL
Two numbers to compare for inequality.