Square Root

Macros
#define	Q12QUARTER
	Q15 square root function. More...
#define	Q28QUARTER
	Q31 square root function. More...

Functions
__STATIC_FORCEINLINE arm_status	arm_sqrt_f32 (const float32_t in, float32_t *pOut)
	Floating-point square root function. More...
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...
__STATIC_FORCEINLINE arm_status	arm_sqrt_f16 (float16_t in, float16_t *pOut)
	Floating-point square root function. More...

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]

Macro Definition Documentation

#define Q12QUARTER

Parameters

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

Returns

execution status

• ARM_MATH_SUCCESS : input value is positive
• ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0

#define Q28QUARTER

Parameters

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

Returns

execution status

• ARM_MATH_SUCCESS : input value is positive
• ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0

Function Documentation

__STATIC_FORCEINLINE arm_status arm_sqrt_f16	(	float16_t	in,
		float16_t *	pOut
	)

Parameters

[in]	in	input value
[out]	pOut	square root of input value

Returns

execution status

• ARM_MATH_SUCCESS : input value is positive
• ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0

__STATIC_FORCEINLINE arm_status arm_sqrt_f32	(	const float32_t	in,
		float32_t *	pOut
	)

Parameters

[in]	in	input value
[out]	pOut	square root of input value

Returns

execution status

• ARM_MATH_SUCCESS : input value is positive
• ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0

arm_status arm_sqrt_q15	(	q15_t	in,
		q15_t *	pOut
	)

Parameters

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

Returns

execution status

• ARM_MATH_SUCCESS : input value is positive
• ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0

arm_status arm_sqrt_q31	(	q31_t	in,
		q31_t *	pOut
	)

Parameters

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

Returns

execution status

• ARM_MATH_SUCCESS : input value is positive
• ARM_MATH_ARGUMENT_ERROR : input value is negative; *pOut is set to 0