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HYPOT(3) BSD Library Functions Manual HYPOT(3) NAME hypot, hypotf, hypotl, cabs, cabsf, cabsl -- Euclidean distance and com- plex absolute value functions LIBRARY Math Library (libm, -lm) SYNOPSIS #include <math.h> double hypot(double x, double y); float hypotf(float x, float y); long double hypotl(long double x, long double y); #include <complex.h> double cabs(double complex z); float cabsf(float complex z); long double cabsl(long double complex z); DESCRIPTION The hypot(), hypotf() and hypotl() functions compute the sqrt(x*x+y*y) in such a way that underflow will not happen, and overflow occurs only if the final result deserves it. The cabs(), cabsf() and cabsl() functions compute the complex absolute value of z. hypot(infinity, v) = hypot(v, infinity) = +infinity for all v, including NaN. ERROR (due to Roundoff, etc.) Below 0.97 ulps. Consequently hypot(5.0, 12.0) = 13.0 exactly; in gen- eral, hypot and cabs return an integer whenever an integer might be ex- pected. NOTES As might be expected, hypot(v, NaN) and hypot(NaN, v) are NaN for all finite v. But programmers might be surprised at first to discover that hypot(+-infinity, NaN) = +infinity. This is intentional; it happens be- cause hypot(infinity, v) = +infinity for all v, finite or infinite. Hence hypot(infinity, v) is independent of v. Unlike the reserved oper- and fault on a VAX, the IEEE NaN is designed to disappear when it turns out to be irrelevant, as it does in hypot(infinity, NaN). SEE ALSO carg(3), math(3), sqrt(3) STANDARDS The hypot(), hypotf(), hypotl(), cabs(), cabsf(), and cabsl() functions conform to ISO/IEC 9899:1999 ("ISO C99"). HISTORY Both a hypot() function and a cabs() function appeared in Version 7 AT&T UNIX. BSD March 30, 2008 BSD
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | ERROR (due to Roundoff, etc.) | NOTES | SEE ALSO | STANDARDS | HISTORY
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