Transposed matrices don't have .ss attribute such as A.T.ss.

Matrix and expressions such as MatrixExpression all have .ss. For expressions, .ss computes the value of expression. TransposedMatrix is kind of in-between being a regular matrix and an expression, b/c methods on a transposed matrix don't first compute the transpose (except e.g. .new).

So, for .ss attribute to be added to TransposedMatrix, I think we would need to update the methods on .ss to be like e.g. ewise_mult, which can handle either a Matrix or a TranposedMatrix.