## Linux and UNIX Man Pages

Test Your Knowledge in Computers #290
Difficulty: Easy
Free and open-source software (FOSS) is software that anyone is freely licensed to use, copy, study, and change the software in any way, and but the source code must be maintained secretly.
True or False?

# cabs(3m) [bsd man page]

HYPOT(3M)																 HYPOT(3M)

NAME
hypot, cabs - Euclidean distance, complex absolute value SYNOPSIS
#include <math.h> double hypot(x,y) double x,y; double cabs(z) struct {double x,y;} z; DESCRIPTION
Hypot(x,y) and cabs(x,y) return sqrt(x*x+y*y) computed 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 all v, including NaN. ERROR (due to Roundoff, etc.) Below 0.97 ulps. Consequently hypot(5.0,12.0) = 13.0 exactly; in general, hypot and cabs return an integer whenever an integer might be expected. The same cannot be said for the shorter and faster version of hypot and cabs that is provided in the comments in cabs.c; its error can exceed 1.2 ulps. NOTES
As might be expected, hypot(v,NaN) and hypot(NaN,v) are NaN for all finite v; 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 infinity) might be surprised at first to discover that hypot(+-infin- ity,NaN) = +infinity. This is intentional; it happens because hypot(infinity,v) = +infinity for all v, finite or infinite. Hence hypot(infinity,v) is independent of v. Unlike the reserved operand 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
math(3M), sqrt(3M) AUTHOR
W. Kahan 4th Berkeley Distribution May 12, 1986 HYPOT(3M)

## Check Out this Related Man Page

HYPOT(3)						   BSD Library Functions Manual 						  HYPOT(3)

NAME
hypot, hypotf, hypotl, cabs, cabsf, cabsl -- Euclidean distance and complex 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 general, hypot and cabs return an integer whenever an integer might be expected. 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 because hypot(infinity, v) = +infinity for all v, finite or infinite. Hence hypot(infinity, v) is independent of v. Unlike the reserved operand 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

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