SIN(3Cg)

NAME
sin - returns sine of scalars and vectors.

SYNOPSIS
  float  sin(float a);
  float1 sin(float1 a);
  float2 sin(float2 a);
  float3 sin(float3 a);
  float4 sin(float4 a);

  half   sin(half a);
  half1  sin(half1 a);
  half2  sin(half2 a);
  half3  sin(half3 a);
  half4  sin(half4 a);

  fixed  sin(fixed a);
  fixed1 sin(fixed1 a);
  fixed2 sin(fixed2 a);
  fixed3 sin(fixed3 a);
  fixed4 sin(fixed4 a);

PARAMETERS

a   Vector or scalar of which to determine the sine.

DESCRIPTION
Returns the sine of a in radians. The return value is in the range [-1,+1].

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

REFERENCE IMPLEMENTATION
sin is best implemented as a native sine instruction, however sin for a float scalar could be implemented by an approximation like this.

  float sin(float a)
  {
    /* C simulation gives a max absolute error of less than 1.8e-7 */
    float4 c0 = float4( 0.0,            0.5,
                        1.0,            0.0            );
    float4 c1 = float4( 0.25,          -9.0,
                        0.75,           0.159154943091 );
    float4 c2 = float4( 24.9808039603, -24.9808039603,
                       -60.1458091736,  60.1458091736  );
    float4 c3 = float4( 85.4537887573, -85.4537887573,
                       -64.9393539429,  64.9393539429  );
    float4 c4 = float4( 19.7392082214, -19.7392082214,
                       -1.0,            1.0            );

    /* r0.x = sin(a) */
    float3 r0, r1, r2;

    r1.x  = c1.w * a - c1.x;                // only difference from cos!
    r1.y  = frac( r1.x );                   // and extract fraction
    r2.x  = (float) ( r1.y < c1.x );        // range check: 0.0 to 0.25
    r2.yz = (float2) ( r1.yy >= c1.yz );    // range check: 0.75 to 1.0
    r2.y  = dot( r2, c4.zwz );              // range check: 0.25 to 0.75
    r0    = c0.xyz - r1.yyy;                // range centering
    r0    = r0 * r0;
    r1    = c2.xyx * r0 + c2.zwz;           // start power series
    r1    =     r1 * r0 + c3.xyx;
    r1    =     r1 * r0 + c3.zwz;
    r1    =     r1 * r0 + c4.xyx;
    r1    =     r1 * r0 + c4.zwz;
    r0.x  = dot( r1, -r2 );                 // range extract

    return r0.x;
  }

PROFILE SUPPORT
sin is fully supported in all profiles unless otherwise specified.

sin is supported via an approximation (shown above) in the vs_1_1, vp20, and arbvp1 profiles.

sin is unsupported in the fp20, ps_1_1, ps_1_2, and ps_1_3 profiles.

SEE ALSO
asin, cos, dot, frac, sincos, tan