Matrices in Excel
This is elementary, but now that I am using it so often, I thought I’d note it down.
MMULT  Matrix multiplication. (For multiplication, number of columns in Matrix 1 should be same as the number of rows in matrix 2.) 

MDETERM  Matrix determinant. (Determinants are defined only for square matrices.) 
MINVERSE  Matrix inversion. (A matrix has an inverse if and only if it is a square matrix, which has a nonzero determinant.) 
TRANSPOSE  Transpose of a matrix. 
For all these to work, preselect a product (or a result) area^{1}, enter the formula in its topleft cell, hold Ctrl
and Shift
, and press Enter
.
A colleague helped run the matrix on his Matlab license and I finally have a benchmark to compare the results with. Matlab is unsurprisingly consistent in its results.

Product or result area should have the exact number of rows and columns the resulting matrix would be. For results of large matrices, I preborder the result area, which makes selection of result area on the worksheet easy. ↩