NAME

atan - returns arctangent of scalars and vectors.

SYNOPSIS

  float  atan( float  a );
  float1 atan( float2 a );
  float2 atan( float2 a );
  float3 atan( float3 a );
  float4 atan( float4 a );
 
  half   atan( half  a );
  half1  atan( half2 a );
  half2  atan( half2 a );
  half3  atan( half3 a );
  half4  atan( half4 a );
 
  fixed  atan( fixed  a );
  fixed1 atan( fixed2 a );
  fixed2 atan( fixed2 a );
  fixed3 atan( fixed3 a );
  fixed4 atan( fixed4 a );

PARAMETERS

a

Vector or scalar of which to determine the arctangent.

DESCRIPTION

Returns the arctangent of x in the range of -pi/2 to pi/2 radians.

For vectors, the returned vector contains the arctangent of each element of the input vector.

REFERENCE IMPLEMENTATION

atan for a float scalar could be implemented like this.

  float atan(float x) {
      return atan2(x, float(1));
  }

atan2 is typically implemented as an approximation.

PROFILE SUPPORT

atan is supported in all profiles except fp20.

SEE ALSO

abs, acos, asin, atan2. sqrt, tan