Function arm_rsqrt_f16

Function Documentation

arm_cmsis_nn_status arm_rsqrt_f16(const float16_t *input, float16_t *output, int32_t block_size)

Elementwise reciprocal square root of a float16 tensor, 1 / sqrt(x).

Same value path as arm_nn_sqrt_f16: widen to float32, evaluate 1.0f / sqrtf(x) there, round once to float16, and so also immune to FPSCR.FZ. Verified exhaustively: for every positive finite float16 input, subnormals included, the result is the correctly rounded float16 of the float64 reciprocal square root (0 ulp, #295). Special values are decided on the bit pattern and returned as literals: +0 -> +Inf, -0 -> -Inf, +Inf -> +0, negative (including -Inf) -> quiet NaN 0x7E00, NaN -> the same NaN with the quiet bit set (sign and payload kept).

Parameters:

  • input – [in] Pointer to the input tensor.

  • output – [out] Pointer to the output tensor; may alias input.

  • block_size – [in] Number of tensor elements.

Returns:

ARM_CMSIS_NN_SUCCESS on success or ARM_CMSIS_NN_ARG_ERROR on invalid arguments.