Implementing the MATLAB interp1 function in J2ME

Question

I am looking to implement interp1 interpolation, 1-D data (search in a table), a function available in MATLAB in J2ME or JAVA. here is the link

http://www.mathworks.com/access/helpdesk/help/techdoc/ref/interp1.html

Is there any library in J2ME or JAVA that has already implemented the same function? If no one can help me implement the interp1 function in J2ME or JAVA?

Answer 1

I just found out the method used for linear interpolation if the "linear" parameter is selected for the syntax of the interp1 function, which is: interp1 (x, y, xi, 'linear'). This is implemented in the interp (double x) method of the LinearInterpolator class, which is present in the multigraph package. link below

http://multigraph.sourceforge.net/multigraph/javadoc/multigraph/LinearInterpolator.html

If u download the package and open the LinearInterpolator.java u file, you can find the code. Package Download Link

http://sourceforge.net/projects/multigraph/files/multigraph/

Answer 2

Example code taken here (linear only):

public static final double[] interpLinear(double[] x, double[] y, double[] xi) throws IllegalArgumentException { if (x.length != y.length) { throw new IllegalArgumentException("X and Y must be the same length"); } if (x.length == 1) { throw new IllegalArgumentException("X must contain more than one value"); } double[] dx = new double[x.length - 1]; double[] dy = new double[x.length - 1]; double[] slope = new double[x.length - 1]; double[] intercept = new double[x.length - 1]; // Calculate the line equation (ie slope and intercept) between each point for (int i = 0; i < x.length - 1; i++) { dx[i] = x[i + 1] - x[i]; if (dx[i] == 0) { throw new IllegalArgumentException("X must be montotonic. A duplicate " + "x-value was found"); } if (dx[i] < 0) { throw new IllegalArgumentException("X must be sorted"); } dy[i] = y[i + 1] - y[i]; slope[i] = dy[i] / dx[i]; intercept[i] = y[i] - x[i] * slope[i]; } // Perform the interpolation here double[] yi = new double[xi.length]; for (int i = 0; i < xi.length; i++) { if ((xi[i] > x[x.length - 1]) || (xi[i] < x[0])) { yi[i] = Double.NaN; } else { int loc = Arrays.binarySearch(x, xi[i]); if (loc < -1) { loc = -loc - 2; yi[i] = slope[loc] * xi[i] + intercept[loc]; } else { yi[i] = y[loc]; } } } return yi; }