Test ``qplot`` Directive with ``liquid-dsp``
============================================

Here is an example showing integration with ``liquid-dsp``:

.. qplot:: series
    :kwargs: {
        "format":{
            "xlabel" : "Time [samples]",
            "xrange" : [0, 120],
            "yrange" : [-1.5, 1.5],
            "legend" : ["input","filtered"]
        },
        "plots": [
            {"ylabel":"Real", "series": [["x-real",{"color":"#aaa"}],["y-real",{"color":"#004080"}]]},
            {"ylabel":"Imag", "series": [["x-imag",{"color":"#aaa"}],["y-imag",{"color":"#004080"}]]}
        ]}
    :width: 65%

    #include <complex.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <math.h>
    #include "liquid.h"
    int main()
    {
        firfilt_crcf q = firfilt_crcf_create_kaiser(11, 0.1f, 40.0f, 0.0f);
        firfilt_crcf_set_scale(q,0.22f);

        printf(" x-real x-imag y-real y-imag\n");
        unsigned int i;
        for (i=0; i<120; i++) {
            float complex x = 1.0f*cexpf(_Complex_I*2*M_PI*0.057f*i) +
                              0.5f*cexpf(_Complex_I*2*M_PI*0.392f*i);
            if      (i==0)  x *= 0.5f;
            else if (i<60)  x *= 1.0f;
            else if (i==60) x *= 0.5f;
            else if (i>60)  x *= 0.0f;
            float complex y;
            firfilt_crcf_execute_one(q, i < 80 ? x : 0, &y);
            printf("%12.8f %12.8f %12.8f %12.8f\n",
                crealf(x), cimagf(x), crealf(y), cimagf(y));
        }
        firfilt_crcf_destroy(q);
        return 0;
    }