Square Root

Functions
arm_status	arm_sqrt_q31 (q31_t in, q31_t *pOut)
	Q31 square root function. More...
arm_status	arm_sqrt_q15 (q15_t in, q15_t *pOut)
	Q15 square root function. More...

Detailed Description

Computes the square root of a number. There are separate functions for Q15, Q31, and floating-point data types. The square root function is computed using the Newton-Raphson algorithm. This is an iterative algorithm of the form:

     x1 = x0 - f(x0)/f'(x0)

where x1 is the current estimate, x0 is the previous estimate, and f'(x0) is the derivative of f() evaluated at x0. For the square root function, the algorithm reduces to:

    x0 = in/2                         [initial guess]
    x1 = 1/2 * ( x0 + in / x0)        [each iteration]

Function Documentation

arm_status arm_sqrt_q15	(	q15_t	in,
		q15_t *	pOut
	)

Q15 square root function.

Parameters

[in]	in	input value. The range of the input value is [0 +1) or 0x0000 to 0x7FFF.
[out]	pOut	square root of input value.

Returns

The function returns ARM_MATH_SUCCESS if input value is positive value or ARM_MATH_ARGUMENT_ERROR if in is negative value and returns zero output for negative values.

Parameters

[in]	in	input value. The range of the input value is [0 +1) or 0x0000 to 0x7FFF.
[out]	*pOut	square root of input value.

Returns

The function returns ARM_MATH_SUCCESS if the input value is positive and ARM_MATH_ARGUMENT_ERROR if the input is negative. For negative inputs, the function returns *pOut = 0.

Definition at line 62 of file arm_sqrt_q15.c.

arm_status arm_sqrt_q31	(	q31_t	in,
		q31_t *	pOut
	)

Q31 square root function.

Parameters

[in]	in	input value. The range of the input value is [0 +1) or 0x00000000 to 0x7FFFFFFF.
[out]	pOut	square root of input value.

Returns

The function returns ARM_MATH_SUCCESS if input value is positive value or ARM_MATH_ARGUMENT_ERROR if in is negative value and returns zero output for negative values.

Parameters

[in]	in	input value. The range of the input value is [0 +1) or 0x00000000 to 0x7FFFFFFF.
[out]	*pOut	square root of input value.

Returns

The function returns ARM_MATH_SUCCESS if the input value is positive and ARM_MATH_ARGUMENT_ERROR if the input is negative. For negative inputs, the function returns *pOut = 0.

Definition at line 61 of file arm_sqrt_q31.c.