MatrixUtils.java

package edu.cmu.sphinx.util;

import java.text.DecimalFormat;

/** Some simple matrix and vector manipulation methods. */
public class MatrixUtils {

    public static final DecimalFormat df = new DecimalFormat("0.00");


    public static String toString(double[][] m) {
        StringBuilder s = new StringBuilder("[");

        for (double[] row : m) {
            s.append(toString(row));
            s.append('\n');
        }

        return s.append(" ]").toString();
    }


    public static String toString(double[] m) {
        StringBuilder s = new StringBuilder("[");

        for (double val : m) {
            s.append(' ').append(df.format(val));
        }

        return s.append(" ]").toString();
    }


    public static int numCols(double[][] m) {
        return m[0].length;
    }


    public static String toString(float[][] matrix) {
        return toString(float2double(matrix));
    }


    public static float[] double2float(double[] values) { // what a mess !!! -> fixme: how to convert number arrays ?
        float[] newVals = new float[values.length];
        for (int i = 0; i < newVals.length; i++) {
            newVals[i] = (float) values[i];
        }

        return newVals;
    }


    public static float[][] double2float(double[][] array) {
        float[][] floatArr = new float[array.length][array[0].length];
        for (int i = 0; i < array.length; i++)
            floatArr[i] = double2float(array[i]);

        return floatArr;
    }


    public static double[] float2double(float[] values) {
        double[] doubArr = new double[values.length];
        for (int i = 0; i < doubArr.length; i++)
            doubArr[i] = values[i];

        return doubArr;
    }


    public static double[][] float2double(float[][] array) {
        double[][] doubArr = new double[array.length][array[0].length];
        for (int i = 0; i < array.length; i++)
            doubArr[i] = float2double(array[i]);

        return doubArr;
    }
}