`fpsinpix``x`procedure`fpcospix``x`procedure`fptanpix``x`procedure- x
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`(fpsin (* pi x))`,`(fpcos (* pi x))`and`(fptan (* pi x))`, respectively, but accurate near roots and singularities. When`x = (+ n 0.5)`for some integer`n`,`(fptanpix x) = +nan.0`.