Hello Magnus

If you need "real" matrix multiplication you need Dot ( . ).

Otherwise the matrices A, B get multiplied element by element a(i,j)*b(i,j).

Robert

I think there are heuristics used to decide when asterisk means Times (in the sense of the Mathematica operation) and when it means Dot. So there can be cases where these simply fail to guess correctly the intention of the user.

Oh sorry, I only put the queries as description of the corresponding pictures.

Actually, I just found the source of the weirdness: The first query is

inverse (((1,2,3),(-1,0,1),(2,1,1)) * (inverse ((1,-2,0),(1,-3,0),(3,-2,1))))

the successful one ist

inverse (((1,2,3),(-1,0,1),(2,1,1)) * ((3,-2,0),(1,-1,0),(-7,4,1)))

If I instead of the " * " use " . ", the first query is working as expected as well. Looking at the examples now, the dot is used for matrix products, but for some instances the asterisk yields the same result as the dot, which lead me to believe they're interchangeable.

I didn't find an example of what the asterisk should actually do, so is it expected that it does something different when used in the first query?