LOGICAL FUNCTION DLAISNAN(DIN1,DIN2) * * -- LAPACK auxiliary routine (version 3.1) -- * Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. * November 2006 * * .. Scalar Arguments .. DOUBLE PRECISION DIN1,DIN2 * .. * * 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. * * 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. * * Arguments * ========= * * DIN1 (input) DOUBLE PRECISION * DIN2 (input) DOUBLE PRECISION * Two numbers to compare for inequality. * * ===================================================================== * * .. Executable Statements .. DLAISNAN = (DIN1.NE.DIN2) RETURN END