[matlab] when matrix multiplication in Simulink user-defined function does not work properly, matrix multiplication module in module library can be used instead

Generally speaking , Matrix multiplication in user-defined functions will be normal ……

Test1

function y = fcn(u)
A = rand(4,3);
y = A*u;

But my friend did have this problem when he was writing , Here's the picture , The input is a 31 Matrix , In the custom function with a 43 Matrix multiplication of , It's still a 4*3 Matrix

The back is really not good , Accept the custom function by x Calculation Ax Become output A, Module calculation using matrix multiplication Ax, To make it work properly

I don't know what magic operation this is, but it may have something to do with other modules , But it's complicated