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1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| 2 | .\" | |
| 3 | .\" Permission is granted to make and distribute verbatim copies of this | |
| 4 | .\" manual provided the copyright notice and this permission notice are | |
| 5 | .\" preserved on all copies. | |
| 6 | .\" | |
| 7 | .\" Permission is granted to copy and distribute modified versions of this | |
| 8 | .\" manual under the conditions for verbatim copying, provided that the | |
| 9 | .\" entire resulting derived work is distributed under the terms of a | |
| 10 | .\" permission notice identical to this one. | |
| c13182ef | 11 | .\" |
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12 | .\" Since the Linux kernel and libraries are constantly changing, this |
| 13 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
| 14 | .\" responsibility for errors or omissions, or for damages resulting from | |
| 15 | .\" the use of the information contained herein. The author(s) may not | |
| 16 | .\" have taken the same level of care in the production of this manual, | |
| 17 | .\" which is licensed free of charge, as they might when working | |
| 18 | .\" professionally. | |
| c13182ef | 19 | .\" |
| fea681da MK |
20 | .\" Formatted or processed versions of this manual, if unaccompanied by |
| 21 | .\" the source, must acknowledge the copyright and authors of this work. | |
| 22 | .\" | |
| 23 | .\" References consulted: | |
| 24 | .\" Linux libc source code | |
| 25 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
| 26 | .\" 386BSD man pages | |
| 27 | .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) | |
| 28 | .\" Modified 2002-07-27 by Walter Harms | |
| 29 | .\" (walter.harms@informatik.uni-oldenburg.de) | |
| 30 | .\" | |
| 31 | .TH ATAN2 3 2002-07-27 "" "Linux Programmer's Manual" | |
| 32 | .SH NAME | |
| 33 | atan2, atan2f, atan2l \- arc tangent function of two variables | |
| 34 | .SH SYNOPSIS | |
| 35 | .nf | |
| 36 | .B #include <math.h> | |
| 1cdac39d | 37 | |
| fea681da | 38 | .BI "double atan2(double " y ", double " x ); |
| fea681da | 39 | .BI "float atan2f(float " y ", float " x ); |
| fea681da | 40 | .BI "long double atan2l(long double " y ", long double " x ); |
| 1cdac39d | 41 | |
| fea681da | 42 | .fi |
| 20c58d70 | 43 | Link with \fI\-lm\fP. |
| fea681da | 44 | .SH DESCRIPTION |
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45 | The |
| 46 | .BR atan2 () | |
| 47 | function calculates the arc tangent of the two | |
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48 | variables \fIx\fP and \fIy\fP. |
| 49 | It is similar to calculating the | |
| 646b2977 | 50 | arc tangent of \fIy\ /\ x\fP, except that the signs of both |
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51 | arguments are used to determine the quadrant of the result. |
| 52 | .SH "RETURN VALUE" | |
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53 | The |
| 54 | .BR atan2 () | |
| 55 | function returns the result in radians, which | |
| 4d9b6984 | 56 | is between \-PI and PI (inclusive). |
| fea681da | 57 | .SH "CONFORMING TO" |
| 68e1685c | 58 | SVr4, POSIX.1-2001, 4.3BSD, C89. |
| c13182ef | 59 | The |
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60 | .I float |
| 61 | and | |
| 62 | .I "long double" | |
| 63 | variants are C99 requirements. | |
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64 | .SH "SEE ALSO" |
| 65 | .BR acos (3), | |
| 66 | .BR asin (3), | |
| 67 | .BR atan (3), | |
| 68 | .BR cos (3), | |
| 69 | .BR sin (3), | |
| 70 | .BR tan (3) |