Java: Data Science Made Easy

Using the Apache Commons math API

The Apache Commons math API (http://commons.apache.org/proper/commons-math/) supports a large number of mathematical and statistical operations. The following example illustrates how to perform matrix multiplication.

We start with the declaration and initialization of the A and B matrices:

double[][] A = {     {0.1950, 0.0311},     {0.3588, 0.2203},     {0.1716, 0.5931},     {0.2105, 0.3242}}; double[][] B = {     {0.0502, 0.9823, 0.9472},     {0.5732, 0.2694, 0.916}}; 

Apache Commons uses the RealMatrix class to hold a matrix. In the following code sequence, the corresponding matrices for the A and B matrices are created using the Array2DRowRealMatrix constructor:

RealMatrix aRealMatrix = new Array2DRowRealMatrix(A);