On 12/19/2009 11:45 AM, Wayne Watson wrote: > A 4x1, 1x7, and 1x5 would be examples of a 1D array or matrix, right? > > Are you saying that instead of using a rotational matrix ... > that I should use a 2-D array for rotCW? So why does numpy have a matrix > class? Is the class only used when working with matplotlib? > > To get the scalar value (sum of squares) I had to use a transpose, T, on > one argument.
At this point, you have raised some long standing issues. There are a couple standard replies people give to some of them. E.g., 1. don't use matrices, OR 2. don't mix the use of matrices and arrays Matrices are *always* 2d (e.g., a "row vector" or a "column vector" is 2d). So in fact you should find it quite natural that that transpose was needed. Matrices change * to matrix multiplication and ** to matrix exponentiation. I find this very convenient, especially in a teaching setting, so I use NumPy matrices all the time. Many on this list avoid them completely. Again, if you want a *scalar* as the product of vectors for which you created matrix objects (e.g., a and b), you can just use flat: np.dot(a.flat,b.flat) hth, Alan Isaac _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
