ISNAN
tests whether a floating-point value is an IEEE Not-a-Number (NaN). ISNAN(X)
X | Variable of the type REAL . |
LOGICAL
. The returned value is TRUE
if X is a NaN and FALSE
otherwise. program test_nan implicit none real :: x x = -1.0 x = sqrt(x) if (isnan(x)) stop '"x" is a NaN' end program test_nan
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Licensed under the GNU Free Documentation License, Version 1.3.
https://gcc.gnu.org/onlinedocs/gcc-6.3.0/gfortran/ISNAN.html