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<font face="Courier New">Samuel,<br>
<br>
Thanks for your answer. Simply being the determinant small doesn't
seem a problem when using floating point. Probably the bigger
problem is the presence, somewhere, of very dissimile orders of
magnitude.<br>
<br>
One curious detail in my example is that the solution of the
system when adding these lines (input vector and multiplication by
the inverse matrix):<br>
<br>
V1 = 1;<br>
B = [V1/R1, V1/Z2, 0, 0]';<br>
phi = inv(A) * B;<br>
<br>
the denominator of the resulting node potentials in vector phi
should be of degree 8 but they happen to be just scalars (degree
0) as if the coefficients were below %eps<br>
<br>
Regards,<br>
<br>
Federico <br>
<br>
</font><br>
<div class="moz-cite-prefix">On 09/03/2020 09:36, <a class="moz-txt-link-abbreviated" href="mailto:sgougeon@free.fr">sgougeon@free.fr</a>
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1349770032.280045122.1583757386978.JavaMail.root@zimbra75-e12.priv.proxad.net">
<pre class="moz-quote-pre" wrap="">Hello Federico,
cond() and rcond() do not accept rationals, but the determinant of A is very close to 0:
--> det(A)
ans =
3.573D-10
------------------------
0.0000027s² +7.433D-10s³
This likely explains that the inversion is not reliable.
Regards
Samuel
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