Update README

Author: ppizarror

README.md

@@ -14,7 +14,7 @@ Normalized spectrogram to seismic acceleration written in *Matlab*. The algorith
 The normalized spectrogram function is defined by:
 
 ```matlab
-matrix = normspectrogram(t, acc, regname)
+[matrix, matrix_t, matrix_f] = norm_spectrogram(t, acc)
 ```
 
 Where:
@@ -23,10 +23,69 @@ Where:
 | :-: | :--|
 | t | Time of the seismic accelerogram |
 | acc | Acceleration (g) of the seismic accelerogram |
-| regname | Name of the seismic accelerogram |
 
 
-This function returns a matrix in where columns refer to mean window time, rows are the frequency of the spectrogram and the value of the matrix are the amplitude of the spectrogram from each time-window on each frequency.
+This function returns a **matrix** in where columns refer to mean window time (**matrix_t**), rows are the frequency of the spectrogram (**matrix_f**) and the value of the matrix are the amplitude of the spectrogram from each time-window on each frequency.
+
+To print matrix you should use:
+
+```matlab
+[matrix, matrix_t, matrix_f] = plot_norm_matrix(m, mt, mf, t, acc, regname)
+```
+
+Where:
+
+| Variable | Description |
+| :-: | :--|
+|  m |  	 Normalized matrix |
+|   mt|     Time array from matrix|
+|   mf|      Frequency array from matrix|
+|   t|      Time of the seismic data|
+|   acc|    Acceleration of seismic data|
+|   regname|Name of the seismic data (plot title)|
+
+## Example
+
+Lets suppose that a seismic registry is stored on *data/CNV_APED_201604162359_N_100.txt*, the file structure is like:
+
+```
+0.000000	-6.329500
+0.010000	2.539600
+0.020000	12.822900
+0.030000	9.435300
+0.040000	-5.397100
+0.050000	-14.233900
+...
+```
+
+Then:
+
+```matlab
+$ Load the data
+data = load('data/CNV_APED_201604162359_N_100.txt');
+
+% Set time and acceleration array
+t = data(:, 1);
+acc = data(:, 2) ./ 980; % Convert from cm/s2 to g
+```
+
+After that we will use ```norm_spectrogram``` function
+
+```matlab
+[m, mt, mf] = norm_spectrogram(t, acc);
+```
+
+Then plot:
+
+```matlab
+plot_norm_matrix(m, mt, mf, t, acc, 'APED 2016/04/16 23:59 N-S');
+```
+
+Obtaining:
+
+<p align="center">
+<img src="https://raw.githubusercontent.com/ppizarror/ppizarror.github.io/master/resources/images/normalized-spectrogram/figure.png" width="50%px" height="50%px">
+</p>
 
 ## Licence
 This project is licenced under GPLv2 (GNU General Public License, version 2) [https://www.gnu.org/licenses/gpl-2.0.html].