GNU Octave is a high-level interpreted language, primarily intended for numerical computations. It provides capabilities for the numerical solution of linear and nonlinear problems, and for performing other numerical experiments. It also provides extensive graphics capabilities for data visualization and manipulation. Octave is normally used through its interactive command line interface, but it can also be used to write non-interactive programs. The Octave language is quite similar to Matlab so that most programs are easily portable.
The newer version of Octave has a GUI almost identical to Matlab and with the extensive package database over at Octave Forge, transitioning from Matlab is really seamless. Most Matlab programs will run in Octave without modifications. However, Octave allows some syntax that Matlab doesn’t. The advantage to using Octave is the price-point. It’s completely free.
Basic Example: Plotting and Trendlines
As a basic introductory example, below is a basic example of plotting and calculating a trendline.
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% Our Sample Data B = [2 4 6 8 10 12 14]; C = [3 6 9 11 15 19 21]; % Plot the data scatter(B,C) % hold the current figure hold on ; % Calculate the second order polynomial coeffs of the input data p = polyfit(B,C,2); % Calculate our x-axis from 1 to 15 and stepping by 0.1 x_axis = 1:0.1:15 ; % Using our x_axis, calculate our y values using the poly coeffs y_axis = polyval(p,x_axis) ; % Plot our data plot( X2,Y2 ) hold off |
This results in a simple scatter plot of our sample data with a second order trendline. The coefficients for the trendline are housed in the variable “p”. The resulting plot can be found below.
