CMSIS DSP Software Library: Sine
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Sine
[Fast Math Functions]
Functions
float32_t arm_sin_f32 (float32_t x)
q31_t arm_sin_q31 (q31_t x)
q15_t arm_sin_q15 (q15_t x)
Variables
static const float32_t sinTable [259]
static const q31_t sinTableQ31 [259]
static const q15_t sinTableQ15 [259]
Detailed Description
Computes the trigonometric sine function using a combination of table lookup and cubic 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 1) mapping to [0 2*pi).
The implementation is based on table lookup using 256 values together with cubic interpolation. The steps used are:
Calculation of the nearest integer table index
Fetch the four table values a, b, c, and d
Compute the fractional portion (fract) of the table index.
Calculation of wa, wb, wc, wd
The final result equals a*wa + b*wb + c*wc + d*wd
where
a=Table[index-1];
b=Table[index+0];
c=Table[index+1];
d=Table[index+2];
and
wa=-(1/6)*fract.^3 + (1/2)*fract.^2 - (1/3)*fract;
wb=(1/2)*fract.^3 - fract.^2 - (1/2)*fract + 1;
wc=-(1/2)*fract.^3+(1/2)*fract.^2+fract;
wd=(1/6)*fract.^3 - (1/6)*fract;
Function Documentation
float32_t arm_sin_f32
(
float32_t
x )
Fast approximation to the trigonometric sine function for floating-point data.
Parameters:
[in]xinput value in radians.
Returns:sin(x).
Examples: arm_linear_interp_example_f32.c, and arm_sin_cos_example_f32.c.
Definition at line 192 of file arm_sin_f32.c.
q31_t arm_sin_q31
(
q31_t
x )
Fast approximation to the trigonometric sine function for Q31 data.
Parameters:
[in]xScaled input value in radians.
Returns:sin(x).
The Q31 input value is in the range [0 +1) and is mapped to a radian value in the range [0 2*pi).
Definition at line 133 of file arm_sin_q31.c.
q15_t arm_sin_q15
(
q15_t
x )
Fast approximation to the trigonometric sine function for Q15 data.
Parameters:
[in]xScaled input value in radians.
Returns:sin(x).
The Q15 input value is in the range [0 +1) and is mapped to a radian value in the range [0 2*pi).
Definition at line 103 of file arm_sin_q15.c.
Variable Documentation
const float32_t sinTable[259] [static]
Example code for Generation of Floating-point Sin Table: tableSize = 256; for(n = -1; n < (tableSize + 1); n++)
{
sinTable[n+1]=sin(2*pi*n/tableSize);
}
where pi value is 3.14159265358979
Definition at line 85 of file arm_sin_f32.c.
const q31_t sinTableQ31[259] [static]
Tables generated are in Q31(1.31 Fixed point format) Generation of sin values in floating point: tableSize = 256;
for(n = -1; n < (tableSize + 1); n++)
{
sinTable[n+1]= sin(2*pi*n/tableSize);
} where pi value is 3.14159265358979
Convert Floating point to Q31(Fixed point): (sinTable[i] * pow(2, 31))
rounding to nearest integer is done sinTable[i] += (sinTable[i] > 0 ? 0.5 :-0.5);
Definition at line 56 of file arm_sin_q31.c.
const q15_t sinTableQ15[259] [static]
Example code for Generation of Q15 Sin Table:
tableSize = 256;
for(n = -1; n < (tableSize + 1); n++)
{
sinTable[n+1]=sin(2*pi*n/tableSize);
} where pi value is 3.14159265358979
Convert Floating point to Q15(Fixed point): (sinTable[i] * pow(2, 15))
rounding to nearest integer is done sinTable[i] += (sinTable[i] > 0 ? 0.5 :-0.5);
Definition at line 58 of file arm_sin_q15.c.
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