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HP-UX Reference > Aatan2d(3M)HP-UX 11i Version 3: February 2007 |
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NAMEatan2d(), atan2df(), atan2dl(), atan2dw(), atan2dq() — degree-valued arctangent-and-quadrant functions DESCRIPTIONatan2d() is a degree-valued version of the atan2() function. It returns the arctangent of y/x, in the range -180 to 180, using the signs of both arguments to determine the quadrant of the return value. atan2df() is a float version of atan2d(); it takes float arguments and returns a float result. USAGETo use these functions compile either with the default -Ae option or with the -Aa and the -D_HPUX_SOURCE options. To use (for Integrity servers) atan2dw() or atan2dq(), compile also with the -fpwidetypes option. To use any of these functions, make sure your program includes <math.h>, and link in the math library by specifying -lm on the compiler or linker command line. For more information, see the HP-UX floating-point guide for HP Integrity servers at the following site: http://www.hp.com/go/fp. RETURN VALUEIf y is ±0 and x is -0, atan2d() returns ±180 respectively. If y is ±0 and x is +0, atan2d() returns ±0 respectively. If y is ±0 and x is less than zero, atan2d() returns ±180 respectively. If y is ±0 and x is greater than zero, atan2d() returns returns ±0 respectively. If y is less than zero and x is zero, atan2d() returns -90. If y is greater than zero and x is zero, atan2d() returns 90. If y is greater than zero and x is -INFINITY, atan2d() returns 180. If y is less than zero and x is -INFINITY, atan2d() returns -180. If y is greater than zero and x is INFINITY, atan2d() returns +0. If y is less than zero and x is INFINITY, atan2d() returns -0. If y is ±INFINITY and x is finite, atan2d() returns ±90 respectively. If y is ±INFINITY and x is -INFINITY, atan2d() returns ±135 respectively. If y is ±INFINITY and x is +INFINITY, atan2d() returns ±45 respectively. If x or y is NaN, atan2d() returns NaN. |
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