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<font face="Courier New">Stéphane,<br>
<br>
You may try, if k is the index,<br>
<br>
pi(2)(k)/pi(3)(k)<br>
<br>
This is because a rational is a list and the first element is a
vector of strings describing the structure, not a component of the
matrix of rationals. <br>
<br>
Indeed I think there is not such a thing as a matrix of rationals,
but a rational (so, itself a list) whose components 2 and 3 are
matrices of polynomials; respectively, numerator and denominator
polynomials. <br>
<br>
When one tries to create a matrix of lists (general lists, not
rationals) it yields an error:<br>
<br>
a = list( 1, "a", %s);<br>
b = list( 2, "b", %z);<br>
c = [a,b]<br>
<br>
The error message is<br>
<br>
Undefined operation for the given operands.<br>
check or define function %l_c_l for overloading.<br>
<br>
When the lists are specifically rtationals, the command works
fine, for instance<br>
<br>
d = [(1+%s)/(1+2*%s), (1-%s)/(1+%s+2*%s^2)]<br>
<br>
but it is not a matrix of rationals but a rational whose numerator
and denominator fields are matrices of polynomials<br>
<br>
Regards,<br>
<br>
Federico Miyara <br>
<br>
</font><br>
<div class="moz-cite-prefix">On 22/07/2021 17:08, Stéphane Mottelet
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:df13c5fa-73d0-88b5-d00a-cd42613df7e8@utc.fr">Hi all, <br>
<br>
I thought indexing an array of rationals was possible. Likely this
is no possible and this is a pity <br>
<br>
--> pi <br>
pi = <br>
<br>
θ +2θ² <br>
---------- <br>
1 +4θ +3θ² <br>
<br>
0.3333333θ <br>
------------ <br>
0.3333333 +θ <br>
<br>
0.3333333θ <br>
------------ <br>
0.3333333 +θ <br>
<br>
θ +2θ² <br>
---------- <br>
1 +4θ +3θ² <br>
<br>
--> pi(1) <br>
ans = <br>
<br>
"r" "num" "den" "dt" <br>
<br>
Any clue, somebody ? <br>
<br>
</blockquote>
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