Christian,
Thanks for the explanation. It's a pity that our documentation didn't make
it clearer that Maxima supports subscripted variables, just like most other
programming languages. Maxima subscripted variables can be strictly
symbolic (without a value), e.g.
sum(a[mod(i,3)],i,0,10) => 3*d[2]+4*d[1]+4*d[0]
or be assigned values:
for i thru 10 do x[i]:i^3$
x[5] => 125
They can of course be assigned *symbolic* values as well:
for i thru 10 do y[i]: trigexpand(sin(x+%pi*i/3))$
y[4] => -sin(x)/2-sqrt(3)*cos(x)/2
Maxima can also subscript list values:
ll: [3,1,4,1,5]$
ll[3] => 4
ll[1] : -7$
ll => [-7,1,4,1,5]
Things get more complicated with declared arrays, which I recommend you
avoid for now.
I hope this helps.
-s
On Wed, Sep 25, 2013 at 4:41 PM, Christian Stengg
<christian.stengg at gmx.at>wrote:
> Thanks for your help. I am a maxima-autodidact and I am using Maxima a
> lot in my daily work as a teacher. I looked for a way to create variables
> (respectively names of variables) "dynamically" and learned about concat in
> the reference guide and about ''(...) by trial and error. I did not know of
> a[i] so far.
>
> Christian
>
> Am 25.09.2013 13:16, schrieb Stavros Macrakis:
>
> ''(...) Is *read-time* substitution, a very special-purpose mechanism.
> Try ev(...).
>
> But why are you creating variables in this strange way in the first place?
> Why not use a[i]?
>
> Also, how did you learn about ''(...) and concat? I wonder if there's some
> documentation or tutorial that's miseducating people... we see this problem
> often.
>
> -s
> On Sep 25, 2013 5:21 AM, "Christian Stengg" <christian.stengg at gmx.at>
> wrote:
>
>> Hello,
>>
>> why do I get the output bj in the loop?
>>
>> Thanks for any help,
>> Christian
>>
>>
>> i:1;
>> concat(a,i)::10*i;
>> ''(concat(a,i));
>> print(''(concat(a,i)));
>>
>> for j:1 thru 2 do (
>> concat(b,j)::10*j,
>> print(''(concat(b,j)))
>> );
>>
>> b1;
>> b2;
>>
>>
>> (%o1) 1
>> (%o2) 10
>> (%o3) 10
>> 10
>> (%o4) 10
>> bj
>> bj
>> (%o5) done
>> (%o6) 10
>> (%o7) 20
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