26 Numerics library [numerics]

26.9 Mathematical functions for floating-point types [c.math]

26.9.3 Three-dimensional hypotenuse [c.math.hypot3]

float hypot(float x, float y, float z); double hypot(double x, double y, double z); long double hypot(long double x, long double y, long double z);

Returns: √x^2+y^2+z^2 .