sqrt vs fast inverse sqrt (v3)

Revision 3 of this benchmark created on

Setup

var approx_const_32, approx_const_64, approx_const_quake_32, fastInvSqrt_typed;
      approx_const_quake_32 = 0x5f3759df;
      approx_const_32 = 0x5f375a86;
      approx_const_64 = 0x5fe6eb50c7aa19f9;
      fastInvSqrt_typed = function(n, precision) {
        var i, iter, y;
        if (precision == null) {
          precision = 1;
        }
        y = new Float32Array(1);
        i = new Int32Array(y.buffer);
        y[0] = n;
        i[0] = 0x5f375a86 - (i[0] >> 1);
        for (iter = 1; 1 <= precision ? iter < precision : iter > precision; 1 <= precision ? iter++ : iter--) {
          y[0] = y[0] * (1.5 - ((n * 0.5) * y[0] * y[0]));
        }
        return y[0];
      };
    
    
    rsqrtFloat = new Float32Array(1);
    
    rsqrtInt = new Int32Array(rsqrtFloat.buffer);
    
    rsqrtIntConst32 = 0x5f375a86;
    
    Math.rsqrt = function(num) {
      rsqrtFloat[0] = num;
      rsqrtInt[0] = rsqrtIntConst32 - (rsqrtInt[0] >> 1);
      rsqrtFloat[0] = rsqrtFloat[0] * (1.5 - ((num * 0.5) * rsqrtFloat[0] * rsqrtFloat[0]));
      return rsqrtFloat[0];
    };

Test runner

Ready to run.

Testing in
TestOps/sec
Math.sqrt
Math.sqrt(23428937);
ready
fast inverse sqrt
fastInvSqrt_typed(23428937);
ready

Revisions

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