So I just started doing numeric methods in Java;
// I have a matrix class that has get, set methods for creating matrices; have used those in the method below.
// The method below computes a Matrix and prints as well returns it.
public Matrix computeA(){
int nrows = A.getNumRows();
int ncols = A.getNumCols();
for(int i = 0; i < nrows; i++){
double sum = 0.0;
for (int j = 0; i< ncols; j++){
if (i!=j){
A.setElement(i,j, aijCalc(i,j) );} // aijCalc is numeric method; setElement has parameters (i, j, value)
}
A.print();
return A;
}
Now, here's what I don't understand how to do: The diagonal where i = j, the matrix entry is 1 - (sum of all the aij entries (for i!=j) in that row). How can I code this in the method above?
My current output(without any rounding off looks like this ):
0.0 0.026055555555555554 0.0248125 0.050694444444444445 0.05872222222222222 0.030208333333333334
-0.0053750000000000004 0.0 0.00792361111111111 0.01813194444444444 0.02361111111111111 0.009874999999999998
-0.0013854166666666667 -0.005291666666666666 0.0 0.008680555555555556 0.009041666666666667 0.0
0.0 0.009041666666666667 0.008680555555555556 0.0 -0.005291666666666666 -0.0013854166666666667
0.009874999999999998 0.02361111111111111 0.01813194444444444 0.00792361111111111 0.0 -0.0053750000000000004
0.030208333333333334 0.05872222222222222 0.050694444444444445 0.0248125 0.026055555555555554 0.0
(it has 0s where i = j)
and it's supposed to look like this:
0.810 0.026 0.025 0.051 0.059 0.030
-‐0.005 0.946 0.008 0.018 0.024 0.010
-‐0.001 -‐0.005 0.989 0.009 0.009 0.000
0.000 0.009 0.009 0.989 -‐0.005 -‐0.001
0.010 0.024 0.018 0.008 0.946 -‐0.005
0.030 0.059 0.051 0.025 0.026 0.810
thanks!
Those extra zeroes are effectively "lies".
SUGGESTION: Just format the number to a realistic precision (e.g. four or five decimal places).
EXAMPLE:
System.out.println (String.format ("%11.2f", x);
http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html
PS:
Exactly the same is true of floating-point "printf" just about every other language: including C# and C++.