Matlab vs FFTW. FFT

#include "fftw3.h"
#include <stdio.h>
#include <malloc.h>
 
int main()
{
    int i, L = 8313;
    double *signal;
    fftw_complex *spec;
    fftw_plan p;
    FILE *f = fopen("audio_data.txt", "r");
 
    signal = (double*)calloc(L, sizeof(double));
    spec = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * L);
 
    for(i=0; i<L; ++i)
    {
        fscanf(f, "%lf\n", &signal[i]);
    }
 
    p = fftw_plan_dft_r2c_1d(L, signal, spec, FFTW_ESTIMATE);
    fftw_execute(p);
 
    fftw_destroy_plan(p);
    fftw_free(spec);
    free(signal);
    fclose(f);
    return 0;
}

#include "fftw3.h"
#include <stdio.h>
#include <malloc.h>
#include <math.h>
 
typedef struct
{
    char id_riff[4];
    long len_riff;
 
    char id_chuck[4];
    char fmt[4];
    long len_chuck;
 
    short type;
    short channels;
    long freq;
    long bytes;
    short align;
    short bits;
 
    char id_data[4];
    long len_data;
}titleWave;
 
int main()
{
    int i, L = 0;
    fftw_plan p;
    titleWave title;
    FILE *f = fopen("1-mono.wav", "rb");
    FILE *fRes = fopen("spec.txt", "w");
 
    short *s;
    double *signal;
    fftw_complex *spec;
/*
    fseek(f, 0, SEEK_END);
    L = (ftell(f) - sizeof(titleWave))/ sizeof(short);
    fseek(f, 0, SEEK_SET);
*/
    fread(&title, sizeof(title), 1, f);
    L = title.len_data / sizeof(short);
 
    s = (short*)calloc(L, sizeof(short));
    signal = (double*)calloc(L, sizeof(double));
    spec = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * L/2 +1);
 
    fread(s, sizeof(short), L, f);
 
    for(i=0; i<L; ++i)
    {
        signal[i] = (double)s[i] / (1<<15); // /32768 for normalize
    }
    fclose(f);
    free(s);
 
    p = fftw_plan_dft_r2c_1d(L, signal, spec, FFTW_ESTIMATE);
    fftw_execute(p);
    fftw_destroy_plan(p);
 
    for(i=0; i<L/2; ++i)
    {
        signal[i] = sqrt(spec[i][0] * spec[i][0] + spec[i][1] * spec[i][1]);
        fprintf(fRes, "%f, ", signal[i]);
    }
 
    fftw_free(spec);
    free(signal);
    fclose(fRes);
 
    return 0;
}