Functions | |
float32_t | arm_cos_f32 (float32_t x) |
Fast approximation to the trigonometric cosine function for floating-point data. | |
q15_t | arm_cos_q15 (q15_t x) |
Fast approximation to the trigonometric cosine function for Q15 data. | |
q31_t | arm_cos_q31 (q31_t x) |
Fast approximation to the trigonometric cosine function for Q31 data. | |
Computes the trigonometric cosine function using a combination of table lookup and linear interpolation. There are separate functions for Q15, Q31, and floating-point data types. The input to the floating-point version is in radians while the fixed-point Q15 and Q31 have a scaled input with the range [0 +0.9999] mapping to [0 2*pi). The fixed-point range is chosen so that a value of 2*pi wraps around to 0.
The implementation is based on table lookup using 512 values together with linear interpolation. The steps used are:
(1.0f-fract)*a + fract*b;
where
a = Table[index]; b = Table[index+1];
Fast approximation to the trigonometric cosine function for floating-point data.
[in] | x | input value in radians |
Fast approximation to the trigonometric cosine function for Q15 data.
[in] | x | Scaled input value in radians |
The Q15 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*PI).