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Cosine
[Fast Math Functions]
Computes the trigonometric cosine function using a combination of table lookup and linear interpolation. More...
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. | |
Detailed Description
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 256 values together with linear interpolation. The steps used are:
- Calculation of the nearest integer table index
- Compute the fractional portion (fract) of the table index.
- The final result equals
(1.0f-fract)*a + fract*b;
where
b=Table[index+0];
c=Table[index+1];
Function Documentation
| float32_t arm_cos_f32 | ( | float32_t | x ) |
Fast approximation to the trigonometric cosine function for floating-point data.
- Parameters:
-
[in] x input value in radians.
- Returns:
- cos(x).
Definition at line 82 of file arm_cos_f32.c.
| q15_t arm_cos_q15 | ( | q15_t | x ) |
Fast approximation to the trigonometric cosine function for Q15 data.
- Parameters:
-
[in] x Scaled input value in radians.
- Returns:
- cos(x).
The Q15 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*pi).
Definition at line 62 of file arm_cos_q15.c.
| q31_t arm_cos_q31 | ( | q31_t | x ) |
Fast approximation to the trigonometric cosine function for Q31 data.
- Parameters:
-
[in] x Scaled input value in radians.
- Returns:
- cos(x).
The Q31 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*pi).
Definition at line 62 of file arm_cos_q31.c.
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