diff options
Diffstat (limited to 'gnuradio-runtime/lib/math/fast_atan2f.cc')
| -rw-r--r-- | gnuradio-runtime/lib/math/fast_atan2f.cc | 18 |
1 files changed, 8 insertions, 10 deletions
diff --git a/gnuradio-runtime/lib/math/fast_atan2f.cc b/gnuradio-runtime/lib/math/fast_atan2f.cc index 20e21be32b..f968310ff8 100644 --- a/gnuradio-runtime/lib/math/fast_atan2f.cc +++ b/gnuradio-runtime/lib/math/fast_atan2f.cc @@ -31,7 +31,7 @@ namespace gr { #define TAN_MAP_RES 0.003921569 /* (smallest non-zero value in table) */ #define RAD_PER_DEG 0.017453293 - #define TAN_MAP_SIZE 256 + #define TAN_MAP_SIZE 255 /* arctangents from 0 to pi/4 radians */ static float @@ -99,8 +99,8 @@ namespace gr { 7.551044e-01, 7.571798e-01, 7.592472e-01, 7.613064e-01, 7.633576e-01, 7.654008e-01, 7.674360e-01, 7.694633e-01, 7.714826e-01, 7.734940e-01, 7.754975e-01, 7.774932e-01, - 7.794811e-01, 7.814612e-01, 7.834335e-01, 7.853983e-01, - 7.853983e-01 + 7.794811e-01, 7.814612e-01, 7.834335e-01, 7.853982e-01, + 7.853982e-01 }; @@ -118,7 +118,7 @@ namespace gr { determine the final angle value in the range of -180 to 180 degrees. Note that this function uses the small angle approximation for values close to zero. This routine calculates the arc tangent - with an average error of +/- 0.045 degrees. + with an average error of +/- 3.56e-5 degrees (6.21e-7 radians). *****************************************************************************/ float @@ -135,7 +135,6 @@ namespace gr { if(!((y_abs > 0.0f) || (x_abs > 0.0f))) return 0.0; - //z = (y_abs < x_abs ? y_abs / x_abs : x_abs / y_abs); if(y_abs < x_abs) z = y_abs / x_abs; else @@ -147,14 +146,13 @@ namespace gr { base_angle = z; else { /* find index and interpolation value */ - alpha = z * (float)TAN_MAP_SIZE - .5; - index = (int)alpha & 0xff; + alpha = z * (float)TAN_MAP_SIZE; + index = ((int)alpha) & 0xff; alpha -= (float)index; /* determine base angle based on quadrant and */ /* add or subtract table value from base angle based on quadrant */ - base_angle = fast_atan_table[index]; - base_angle += - (fast_atan_table[index + 1] - fast_atan_table[index]) * alpha; + base_angle = fast_atan_table[index]; + base_angle += (fast_atan_table[index + 1] - fast_atan_table[index]) * alpha; } if(x_abs > y_abs) { /* -45 -> 45 or 135 -> 225 */ |