Question about exponential transfer function

Generally in matlab, exponential transfer function can be used by

       i.e., exp(M*s) where M<0

which means 'input delay', or derived from 'second translation(shifting) theorem' But, how can we analysis exponential transfer function in matlab such that

       i.e., exp(M*s)  where M > 0. ?

Answer 1

[Patrik Ek]

What do you need this for? In general I would say that you cannot do this. Just look att the definition of the laplace transformation. Which is only defined from 0 to infinity. Matlab notice this too by declaring the transfer function as non causal.

 s = tf('s')
 h = exp(2*s)
 Error using tf/exp (line 34)
 In "exp(M*s)", M must have nonpositive entries for causality.