Tests input for NaN.
The FORTRAN 77 interfaces are specified in the mkl_lapack.fi include file (to be used in Fortran programs) and in the mkl_lapack.h include file (to be used in C programs).
This logical routine checks for NaNs (NaN stands for 'Not A Number') 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.
This routine is not for general use. It exists solely to avoid over-optimization in ?isnan.
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