What does it mean by *+ operation

I found someone using *+ in their code, but I don't know what this operation does. For example,

ones(3,3)*+ones(3,3)

yields a 3*3 matrix whose entries are all 3.

Answer 1

[Steven Lord]

In this context + is the unary plus. See the help for uplus. Once MATLAB has applied uplus to the second array, it then performs normal matrix multiplication.

[John ZHANG]

I have checked the help document but I still don't understand what it says. For example, how does the uplus change the value of ones(3,3)?

[John ZHANG]

Is there any difference if I use the normal matrix multiplication directly?