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HYPOT(3) DragonFly Library Functions Manual HYPOT(3)## NAME

hypot,hypotf,hypotl,cabs,cabsf,cabsl-- Euclidean distance and com- plex absolute value functions## SYNOPSIS

#include<math.h>doublehypot(doublex,doubley);floathypotf(floatx,floaty);longdoublehypotl(longdoublex,longdoubley);#include<complex.h>doublecabs(doublecomplexz);floatcabsf(floatcomplexz);longdoublecabsl(longdoublecomplexz);## DESCRIPTION

Thehypot(),hypotf() andhypotl() 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.hypot(infinity,v) =hypot(v,infinity) = +infinity for allv, includingNaN. Thecabs(),cabsf() andcabsl() functions return the absolute value of the complex numberz. ERRORS (due to Roundoff, etc.) Below 0.97ulps. Consequentlyhypot(5.0,12.0) = 13.0 exactly; in gen- eral, hypot and cabs return an integer whenever an integer might be expected.## NOTES

As might be expected,hypot(v,NaN) andhypot(NaN,v) areNaNfor allfinitev; with ``reserved operand'' in place of "NaN", the same is true on a VAX. But programmers on machines other than a VAX (it has no infin- ity) might be surprised at first to discover thathypot(+-infinity,NaN) = +infinity. This is intentional; it happens becausehypot(infinity,v) = +infinity forallv, finite or infinite. Hencehypot(infinity,v) is independent ofv. Unlike the reserved operand fault on a VAX, the IEEENaNis designed to disappear when it turns out to be irrelevant, as it does inhypot(infinity,NaN).## SEE ALSO

sqrt(3)## HISTORY

Ahypot() function first appeared in Version 3 AT&T UNIX, andcabs() in Version 7 AT&T UNIX. DragonFly 4.7 January 15, 2015 DragonFly 4.7

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