Dealing with exp functions



try  ratsubst (A, exp(a1*x4),d1);


Maths & Geometry Crew wrote:

> Given the following expression F:
> 
> (C1) F :  - G1*x6 - 2*a1*DD1*%E^(-2*a1*x4)*(%E^(a1*x4) - 1) - chi*(1-x1)/2;
> 
>                         a1 x4        - 2 a1 x4           chi (1 - x1)
> (D1)      - 2 a1 DD1 (%E      - 1) %E          - G1 x6 - ------------
>                                                               2
> 
> 
> I am trying to factor E^(-a1 x4) out of the first term, to get:
> 
> 
>                             - a1 x4     - a1 x4             chi (1 - x1)
> ...)      - 2 a1 DD1 (1 - %E        ) %E          - G1 x6 - ------------
>                                                               2
> 
>                                - a1 x4 
> so as to be able to replace  %E           with one symbol A
> 
>