1  
 2  /* ----------------------------------------------------------------------
 3   * Project:      CMSIS DSP Library
 4   * Title:        arm_correlation_distance_f32.c
 5   * Description:  Correlation distance between two vectors
 6   *
 7   * $Date:        23 April 2021
 8   * $Revision:    V1.9.0
 9   *
10   * Target Processor: Cortex-M and Cortex-A cores
11   * -------------------------------------------------------------------- */
12  /*
13   * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
14   *
15   * SPDX-License-Identifier: Apache-2.0
16   *
17   * Licensed under the Apache License, Version 2.0 (the License); you may
18   * not use this file except in compliance with the License.
19   * You may obtain a copy of the License at
20   *
21   * www.apache.org/licenses/LICENSE-2.0
22   *
23   * Unless required by applicable law or agreed to in writing, software
24   * distributed under the License is distributed on an AS IS BASIS, WITHOUT
25   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
26   * See the License for the specific language governing permissions and
27   * limitations under the License.
28   */
29  
30  #include "dsp/distance_functions.h"
31  #include <limits.h>
32  #include <math.h>
33  
34  
35  
36  /**
37    @addtogroup Correlation
38    @{
39   */
40  
41  
42  /**
43   * @brief        Correlation distance between two vectors
44   *
45   * The input vectors are modified in place !
46   *
47   * @param[in]    pA         First vector
48   * @param[in]    pB         Second vector
49   * @param[in]    blockSize  vector length
50   * @return distance
51   *
52   */
53  
54  float32_t arm_correlation_distance_f32(float32_t *pA,float32_t *pB, uint32_t blockSize)
55  {
56      float32_t ma,mb,pwra,pwrb,dot,tmp;
57  
58      arm_mean_f32(pA, blockSize, &ma);
59      arm_mean_f32(pB, blockSize, &mb);
60  
61      arm_offset_f32(pA, -ma, pA, blockSize);
62      arm_offset_f32(pB, -mb, pB, blockSize);
63  
64      arm_power_f32(pA, blockSize, &pwra);
65      arm_power_f32(pB, blockSize, &pwrb);
66  
67      arm_dot_prod_f32(pA,pB,blockSize,&dot);
68  
69      dot = dot / blockSize;
70      pwra = pwra / blockSize;
71      pwrb = pwrb / blockSize;
72  
73      arm_sqrt_f32(pwra * pwrb,&tmp);
74   
75      return(1.0f - dot / tmp);
76  
77     
78  }
79  
80  
81  
82  /**
83   * @} end of Correlation group
84   */