const  float  COS_tab[91]=
                  {1.0000,0.9998,0.9993,0.9986,0.9975,0.9962,0.9945,0.9925,0.9903,
                   0.9877,0.9848,0.9816,0.9781,0.9744,0.9703,0.9659,0.9614,0.9563,
                   0.9511,0.9455,0.9397,0.9336,0.9272,0.9205,0.9135,0.9063,0.8988,
                   0.8910,0.8829,0.8746,0.8660,0.8572,0.8480,0.8387,0.8290,0.8192,
                   0.8090,0.7986,0.7880,0.7771,0.7760,0.7547,0.7431,0.7314,0.7193,
                   0.7071,0.6947,0.6820,0.6691,0.6561,0.6428,0.6293,0.6157,0.6018,
                   0.5878,0.5736,0.5592,0.5446,0.5299,0.5150,0.5000,0.4848,0.4695,
                   0.4540,0.4384,0.4226,0.4067,0.3907,0.3746,0.3584,0.3420,0.3256,
                   0.3090,0.2924,0.2757,0.2588,0.2419,0.2250,0.2079,0.1908,0.1736,
                   0.1564,0.1392,0.1219,0.1045,0.0872,0.0698,0.0523,0.0349,0.0174,
                   0.0000};