How to multiply two 1D matrices using JAMA?
This may be a bit of a silly question and I might also have misunderstood the best way to approach this problem but what I essentially want to do is the following:
I want to multiply the following matrices together to get the result -0.8. However I would ideally like to do this using a JAMA function. So far I have the following and I think I'm almost there, it's just the last step I'm stuck on..
// Create the two arrays (in reality I won't be creating these, the two 1D matrices
// will be the result of othe开发者_如何学JAVAr calculations - I have just created them for this example)
double[] aArray = [0.2, -0.2];
double[] bArray = [0, 4];
// Create matrices out of the arrays
Matrix a = new Matrix( aArray, 1 );
Matrix b = new Matrix( bArray, 1 );
// Multiply matrix a by matrix b to get matrix c
Matrix c = a.times(b);
// Turn matrix c into a double
double x = // ... this is where I'm stuck
Any help on this would be really appreciated. Thanks in advance!
Do you mean using get?
double x = c.get(0, 0);
http://math.nist.gov/javanumerics/jama/doc/
It sounds like you're looking for
double x = c.get(0, 0);
Also, your matrices have incompatible dimensions for multiplication. It would appear that the second matrix ought be constructed like so:
Matrix b = new Matrix( bArray, bArray.length );
You can simply use the get() method:
double x = c.get(0,0);
Note that you will get an IllegalArgumentException since you're trying to multiply two row vectors though. From the times()
documentation:
java.lang.IllegalArgumentException - Matrix inner dimensions must agree.
You probably want to make the second array into a column vector.
精彩评论