LAPACK
3.6.1
LAPACK: Linear Algebra PACKage

logical function dlaisnan  (  double precision  DIN1, 
double precision  DIN2  
) 
DLAISNAN tests input for NaN by comparing two arguments for inequality.
Download DLAISNAN + dependencies [TGZ] [ZIP] [TXT]
This routine is not for general use. It exists solely to avoid overoptimization in DISNAN. DLAISNAN checks for NaNs by comparing its two arguments for inequality. NaN is the only floatingpoint 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 wholeprogram optimization may delete this test. The ISNAN functions will be replaced by the correct Fortran 03 intrinsic once the intrinsic is widely available.
[in]  DIN1  DIN1 is DOUBLE PRECISION 
[in]  DIN2  DIN2 is DOUBLE PRECISION Two numbers to compare for inequality. 
Definition at line 76 of file dlaisnan.f.