1fixatan2(3)                     Allegro manual                     fixatan2(3)
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NAME

6       fixatan2  -  Fixed  point  version of the libc atan2() routine. Allegro
7       game programming library.
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SYNOPSIS

10       #include <allegro.h>
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13       fixed fixatan2(fixed y, fixed x);
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DESCRIPTION

16       This is a fixed point version of the libc atan2() routine. It  computes
17       the arc tangent of `y / x', but the signs of both arguments are used to
18       determine the quadrant of the result, and `x' is permitted to be  zero.
19       This function is useful to convert Cartesian coordinates to polar coor‐
20       dinates.  Example:
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22          fixed result;
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24          /* Sets `result' to binary angle 64. */
25          result = fixatan2(itofix(1), 0);
26          /* Sets `result' to binary angle -109. */
27          result = fixatan2(itofix(-1), itofix(-2));
28          /* Fails the assert. */
29          result = fixatan2(0, 0);
30          ASSERT(!errno);
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RETURN VALUE

33       Returns the arc tangent of `y / x' in fixed point binary format  angle,
34       from  `-128'  to  `128'. If both `x' and `y' are zero, returns zero and
35       sets `errno' to EDOM.
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SEE ALSO

39       , exlights(3), exspline(3)
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43Allegro                          version 4.2.2                     fixatan2(3)
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