sgn
fn
F sgn(F)(F x) if (isFloatingPoint!F || isIntegral!F) @safe pure nothrow @nogcReturns -1 if x < 0, x if x == 0, 1 if
x > 0, and NaN if x==NaN.F sgn(F)(F x) if (isFloatingPoint!F || isIntegral!F) @safe pure nothrow @nogcReturns -1 if x < 0, x if x == 0, 1 if
x > 0, and NaN if x==NaN.