For example, instead of writing Det[Matrix imput], I would like to simply put the matrix inside 2 straight lines. Instead of writing Cos[x]^2, I would like to write Cos^2[x], with the square right after the Cos. And instead of writing the differential operator Dx[expression,x], I would like to write Dx[expression], without the x at the end, assuming implicitly the underscript on D means the variable the differentiation is occuring on.
I mean, I would like to be able to write mathematical equations and expressions in Mathematica in exactly the same way I write on a piece of paper. Could you help me?