ASKSAGE: Sage Q&A Forum - RSS feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sun, 28 Jun 2015 03:30:52 +0200Has ticket #6480 been fixed?https://ask.sagemath.org/question/27217/has-ticket-6480-been-fixed/The ticket is:
>.subs_expr() method doesn't work for argument of D derivative operator
Here is an example (from Sage 6.2, which I'm currently using):
var('x,y,f,F,Fx,Fy')
y = function('y',x)
f = function('f',x,y)
d1 = diff(f,x,1)
d1.subs_expr(diff(y,x,1)==F)
F*D[1](f)(x, y(x)) + D[0](f)(x, y(x))
So far, all good. But when I try:
d1.subs_expr(diff(y,x,1)==F,diff(f,x,1)==Fx,diff(f,y,1)==Fy)
I receive the error:
TypeError: argument symb must be a symbol
Maybe my syntax is wrong, so either my question is moot, in which case what am I doing wrong? Or maybe my syntax is correct and the fault is still a ticket for `subs_expr`. Advice as always would be very welcome!Sun, 28 Jun 2015 02:47:35 +0200https://ask.sagemath.org/question/27217/has-ticket-6480-been-fixed/Answer by tmonteil for <p>The ticket is:</p>
<blockquote>
<p>.subs_expr() method doesn't work for argument of D derivative operator </p>
</blockquote>
<p>Here is an example (from Sage 6.2, which I'm currently using):</p>
<pre><code>var('x,y,f,F,Fx,Fy')
y = function('y',x)
f = function('f',x,y)
d1 = diff(f,x,1)
d1.subs_expr(diff(y,x,1)==F)
F*D[1](f)(x, y(x)) + D[0](f)(x, y(x))
</code></pre>
<p>So far, all good. But when I try:</p>
<pre><code>d1.subs_expr(diff(y,x,1)==F,diff(f,x,1)==Fx,diff(f,y,1)==Fy)
</code></pre>
<p>I receive the error:</p>
<pre><code>TypeError: argument symb must be a symbol
</code></pre>
<p>Maybe my syntax is wrong, so either my question is moot, in which case what am I doing wrong? Or maybe my syntax is correct and the fault is still a ticket for <code>subs_expr</code>. Advice as always would be very welcome!</p>
https://ask.sagemath.org/question/27217/has-ticket-6480-been-fixed/?answer=27218#post-id-27218As you can check http://trac.sagemath.org/ticket/6480 the ticket is still open.
Sun, 28 Jun 2015 03:30:52 +0200https://ask.sagemath.org/question/27217/has-ticket-6480-been-fixed/?answer=27218#post-id-27218