I have found an error in vector multiplication when the length of one vector is reduced to just one. It should not throw an error, but does, stating that "These array dimensions do not match", which is just ridiculous.
Of course, there are workarounds, but this should be corrected.
I agree that the symbolic processor has a bug. However, please note that the numeric processor calculates the correct product.
Mostly correct. However, the Lev-Mar method (in genfit and Least SquaresFit) has to resolve the first derivatives of the fitting parameters. That's where I've run afoul of this problem.
How does it fare when the vector (with the lower case letters) is reduced to a single element vector (containing just a)?
In Mathcad 11: