c99 [ flag... ] file... –lm [ library... ] #include <math.h> double hypot(double x, double y);
float hypotf(float x, float y);
long double hypotl(long double x, long double y);
These functions compute the length of the square root of x2 + y2 without undue overflow or underflow.
Upon successful completion, these functions return the length of the hypotenuse of a right angled triangle with sides of length x2 and y2.
If the correct value would cause overflow, a range error occurs and hypot(), hypotf(), and hypotl() return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively.
If x or y is ±Inf, +Inf is returned even if one of x or y is NaN.
If x or y is NaN and the other is not ±Inf, a NaN is returned.
These functions will fail if:
The result overflows.
If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the overflow floating-point exception is raised.
hypot(x,y), hypot(y,x), and hypot(x, −y) are equivalent.
hypot(x, ±0) is equivalent to fabs(x).
These functions takes precautions against underflow and overflow during intermediate steps of the computation.
An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.
See attributes(5) for descriptions of the following attributes: