Re: use solution of solve (symbolic)

[Colin Macdonald]

On 2019-03-27 6:21 p.m., Doug Stewart wrote:
> here is one way
>
> solution=solve([eq1 eq2],[a b])
> a1=solution.a
> b1=solution.b
> double(subs(dbl_a,a,a1))
> double(subs(dbl_b,b,b1))

I agree with Doug.

In the *next* version of Symbolic (2.8.0, not out yet) you will also be 
able to use subs and/or eval to shortcut this a little bit:

syms a b
dbl_a=2*a
dbl_b=2*b
eq1=dbl_a==9
eq2=dbl_b==10
solution=solve([eq1 eq2],[a b])
a = solution.a
b = solution.b
eval(dbl_a)
eval(dbl_b)

The eval command will search your workspace for variables whose names 
match the symbols a and b.

Note: IMHO, this sort of thing might be nice for interactive 
command-line usage, but Doug's approach is better for code.

Colin