problem with "concatting variables"



I hate ev....

      -s
On Sep 26, 2013 3:34 AM, "Jaime Villate" <villate at fe.up.pt> wrote:

>  On 26-09-2013 02:10, Stavros Macrakis wrote:
>
> Why infeval?
>
> Because that's what Redfern, Chandler and Fell propose in their book and I
> have not been able to find an alternative:
>
> (%i2) b2:4$
> (%i3) ev(concat(b,2));
> (%o3) b2
> (%i4) ev(ev(concat (b,2)));
> (%o4) b2
> (%i5) ev(concat (b,2),infeval);
> (%o5) 4
>
> do you know another way to get the value 4 without using ''(...) ?
>
> Jaime
>
>       -s
> On Sep 25, 2013 12:47 PM, "Jaime Villate" <villate at fe.up.pt> wrote:
>
>>  I think that the result Christian was expecting is what you get from:
>>
>> for j:1 thru 2 do (
>>     concat (b,j) :: 10*j,
>>     print (ev (concat (b,j), infeval)));
>>
>> There is a very nice old book: Darren Redfern, Edgar Chandler and Richard
>> N. Fell, Macsyma ODE Lab Book, 1998, where the authors use concat() and
>> ''(...) very intensely.
>> They do switch from ''(concat(...)) to ev(concat(...),infeval) inside for
>> loops.
>>
>> I do agree that concat(...) and ''(...) should be avoided in favor of
>> other better ways to do the same.
>> Regards,
>> Jaime
>>
>
>