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118 lines
2.5 KiB
C
118 lines
2.5 KiB
C
/* ----------------------------------------------------------------------
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* Project: CMSIS DSP Library
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* Title: arm_householder_f64.c
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* Description: Double floating-point Householder transform
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*
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* $Date: 15 June 2022
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* $Revision: V1.11.0
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*
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* Target Processor: Cortex-M and Cortex-A cores
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* -------------------------------------------------------------------- */
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/*
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* Copyright (C) 2010-2022 ARM Limited or its affiliates. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the License); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an AS IS BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "dsp/matrix_functions.h"
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#include "dsp/basic_math_functions.h"
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#include "dsp/fast_math_functions.h"
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#include "dsp/matrix_utils.h"
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#include <math.h>
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/**
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@ingroup groupMatrix
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*/
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/**
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@addtogroup MatrixHouseholder
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@{
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*/
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/**
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@brief Householder transform of a double floating point vector.
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@param[in] pSrc points to the input vector.
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@param[in] threshold norm2 threshold.
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@param[in] blockSize dimension of the vector space.
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@param[out] pOut points to the output vector.
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@return beta return the scaling factor beta
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*/
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float64_t arm_householder_f64(
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const float64_t * pSrc,
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const float64_t threshold,
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uint32_t blockSize,
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float64_t * pOut
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)
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{
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uint32_t i;
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float64_t epsilon;
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float64_t x1norm2,alpha;
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float64_t beta,tau,r;
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epsilon = threshold;
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alpha = pSrc[0];
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for(i=1; i < blockSize; i++)
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{
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pOut[i] = pSrc[i];
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}
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pOut[0] = 1.0;
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arm_dot_prod_f64(pSrc+1,pSrc+1,blockSize-1,&x1norm2);
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if (x1norm2<=epsilon)
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{
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tau = 0.0;
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memset(pOut,0,blockSize * sizeof(float64_t));
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}
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else
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{
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beta = alpha * alpha + x1norm2;
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beta=sqrt(beta);
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if (alpha > 0.0)
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{
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beta = -beta;
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}
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r = 1.0 / (alpha -beta);
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arm_scale_f64(pOut,r,pOut,blockSize);
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pOut[0] = 1.0;
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tau = (beta - alpha) / beta;
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}
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return(tau);
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}
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/**
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@} end of MatrixHouseholder group
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*/
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