将如下matlab代码转成C语言代码 function [idx, pow] = getBestIdx(spec, low, high, num, fs, Nfft, step) % step: 指定间隔多少bpm [~, eIdx] = sort(spec(low:high), 'descend'); % 从大到小排序 eIdx = eIdx + low - 1; cnt = 1; res = zeros(1, num); pow = zeros(1, num); for k = 1 : length(eIdx) aa = (eIdx(k) - step : eIdx(k) + step); aa(aa < low) = low; aa(aa > high) = high; aa = spec(eIdx(k)) - spec(aa); if length(find(aa < 0)) == 0 res(1, cnt) = eIdx(k); pow(1, cnt) = spec(eIdx(k)); cnt = cnt + 1; if cnt > num break; end end end idx = res; pow = pow / max(pow);

以下是将Matlab代码转换为C语言代码的示例：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void getBestIdx(double *spec, int low, int high, int num, double fs, int Nfft, int step, int *idx, double *pow) {
    int i, j, k, cnt;
    int *eIdx;
    double *res, *aa;

    // Allocate memory
    eIdx = (int*) malloc((high - low + 1) * sizeof(int));
    res = (double*) malloc(num * sizeof(double));
    aa = (double*) malloc((2 * step + 1) * sizeof(double));

    // Sort spec from high to low
    for (i = 0; i <= high - low; i++) {
        eIdx[i] = i + low;
    }
    for (i = high - low; i > 0; i--) {
        for (j = 0; j < i; j++) {
            if (spec[eIdx[j] - low] < spec[eIdx[j+1] - low]) {
                int temp = eIdx[j];
                eIdx[j] = eIdx[j+1];
                eIdx[j+1] = temp;
            }
        }
    }

    // Find the best idx
    cnt = 0;
    for (k = 0; k <= high - low; k++) {
        // Calculate aa
        for (i = 0; i <= 2 * step; i++) {
            int idx_aa = eIdx[k] + i - step;
            if (idx_aa < low) idx_aa = low;
            if (idx_aa > high) idx_aa = high;
            aa[i] = spec[eIdx[k] - low] - spec[idx_aa - low];
        }
        // Check if aa is all non-negative
        int is_non_negative = 1;
        for (i = 0; i <= 2 * step; i++) {
            if (aa[i] < 0) {
                is_non_negative = 0;
                break;
            }
        }
        // Update res and pow if aa is all non-negative
        if (is_non_negative) {
            res[cnt] = eIdx[k];
            pow[cnt] = spec[eIdx[k] - low];
            cnt++;
            if (cnt >= num) break;
        }
    }

    // Copy res to idx and normalize pow
    for (i = 0; i < cnt; i++) {
        idx[i] = (int) res[i];
        pow[i] = pow[i] / pow[0];
    }

    // Free memory
    free(eIdx);
    free(res);
    free(aa);
}

int main() {
    double spec[1000];
    int low = 1, high = 100, num = 5, Nfft = 1024, step = 2;
    int idx[num];
    double pow[num], fs = 44100;
    int i;

    // Initialize spec
    for (i = 0; i < 1000; i++) {
        spec[i] = sin(2 * M_PI * i / 1000);
    }

    // Call getBestIdx
    getBestIdx(spec, low, high, num, fs, Nfft, step, idx, pow);

    // Print results
    printf("idx: ");
    for (i = 0; i < num; i++) {
        printf("%d ", idx[i]);
    }
    printf("\n");
    printf("pow: ");
    for (i = 0; i < num; i++) {
        printf("%f ", pow[i]);
    }
    printf("\n");

    return 0;
}

需要注意的是，Matlab中的数组下标是从1开始的，而C语言中的数组下标是从0开始的，因此在将Matlab代码转换为C语言代码时，需要进行相应的修改。另外，Matlab中的sort函数是从小到大排序的，而C语言中的排序函数qsort是从小到大排序的，因此在C语言代码中需要对spec数组进行从大到小的排序。