NAME
asin - returns arcsine of scalars and vectors.
SYNOPSIS
float asin( float a ); float1 asin( float2 a ); float2 asin( float2 a ); float3 asin( float3 a ); float4 asin( float4 a ); half asin( half a ); half1 asin( half2 a ); half2 asin( half2 a ); half3 asin( half3 a ); half4 asin( half4 a ); fixed asin( fixed a ); fixed1 asin( fixed2 a ); fixed2 asin( fixed2 a ); fixed3 asin( fixed3 a ); fixed4 asin( fixed4 a );PARAMETERS
- a
Vector or scalar of which to determine the arcsine.
DESCRIPTION
Returns the arcsine of a in the range [-pi/2,+pi/2], expecting a to be in the range [-1,+1].
For vectors, the returned vector contains the arcsine of each element of the input vector.
REFERENCE IMPLEMENTATION
asin for a float scalar could be implemented like this.
// Handbook of Mathematical Functions // M. Abramowitz and I.A. Stegun, Ed. float asin(float x) { float negate = float(x < 0); x = abs(x); float ret = -0.0187293; ret *= x; ret += 0.0742610; ret *= x; ret -= 0.2121144; ret *= x; ret += 1.5707288; ret = 3.14159265358979*0.5 - sqrt(1.0 - x)*ret; return ret - 2 * negate * ret; }PROFILE SUPPORT
asin is supported in all profiles.
Support in the fp20 is limited.
SEE ALSO