1 /* ----------------------------------------------------------------------
2  * Project:      CMSIS DSP Library
3  * Title:        arm_logsumexp_f64.c
4  * Description:  LogSumExp
5  *
6  * $Date:        23 April 2021
7  * $Revision:    V1.9.0
8  *
9  * Target Processor: Cortex-M and Cortex-A cores
10  * -------------------------------------------------------------------- */
11 /*
12  * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
13  *
14  * SPDX-License-Identifier: Apache-2.0
15  *
16  * Licensed under the Apache License, Version 2.0 (the License); you may
17  * not use this file except in compliance with the License.
18  * You may obtain a copy of the License at
19  *
20  * www.apache.org/licenses/LICENSE-2.0
21  *
22  * Unless required by applicable law or agreed to in writing, software
23  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25  * See the License for the specific language governing permissions and
26  * limitations under the License.
27  */
28 
29 #include "dsp/statistics_functions.h"
30 #include <limits.h>
31 #include <math.h>
32 
33 /**
34  * @addtogroup Entropy
35  * @{
36  */
37 
38 /**
39  * @brief Entropy
40  *
41  * @param[in]  pSrcA        Array of input values.
42  * @param[in]  blockSize    Number of samples in the input array.
43  * @return     Entropy      -Sum(p ln p)
44  *
45  */
46 
arm_entropy_f64(const float64_t * pSrcA,uint32_t blockSize)47 float64_t arm_entropy_f64(const float64_t * pSrcA, uint32_t blockSize)
48 {
49     const float64_t *pIn;
50     uint32_t blkCnt;
51     float64_t accum, p;
52 
53     pIn = pSrcA;
54     blkCnt = blockSize;
55 
56     accum = 0.0f;
57 
58     while(blkCnt > 0)
59     {
60         p = *pIn++;
61 
62         accum += p * log(p);
63 
64         blkCnt--;
65 
66     }
67 
68     return(-accum);
69 }
70 
71 /**
72  * @} end of Entropy group
73  */
74