Estimates the arctangent of Y/X.
- Y [in]
- X [in]
Returns a vector. Each component is an estimate of the arctangent of the corresponding Y component divided by the corresponding X component. Each component is in the range (-PI/2, PI/2).
XMVectorATan2Est returns the following values for the specified special input values.
|Input Value||Return Value|
|Y == 0 and X < 0||Pi with the same sign as Y|
|Y == 0 and X > 0||0 with the same sign as Y|
|Y != 0 and X == 0||Pi / 2 with the same sign as Y|
|X == -Infinity and Y is finite||Pi with the same sign as Y|
|X == +Infinity and Y is finite||0 with the same sign as Y|
|Y == Infinity and X is finite||Pi / 2 with the same sign as Y|
|Y == Infinity and X == -Infinity||3Pi / 4 with the same sign as Y|
|Y == Infinity and X == +Infinity||Pi / 4 with the same sign as Y|
Est functions offer increased performance at the expense of reduced accuracy.
Est functions are appropriate for non-critical calculations where accuracy can be sacrificed for speed.
The exact amount of lost accuracy and speed increase are platform dependent.
This function uses a 9-degree minimax approximation.
Microsoft Visual Studio 2010 or Microsoft Visual Studio 2012 with the Windows SDK for Windows 8. Supported for Win32 desktop apps, Windows Store apps, and Windows Phone 8 apps.