Sage: Ticket #14215: solve with sqrt seems less than powerful
https://trac.sagemath.org/ticket/14215
<pre class="wiki">sage: eq = x == sqrt(x)
sage: solve(eq,x)
[x == sqrt(x)]
sage: solve(eq,x,to_poly_solve=True)
[x == 0, x == 1]
sage: eq = x^2 == sqrt(x)
sage: solve(eq,x,to_poly_solve=True)
[x == x^(1/4), x == 0]
sage: eq = x^2 == -sqrt(x)
sage: solve(eq,x,to_poly_solve=True)
[x == sqrt(-sqrt(x)), x == 1/2*I*sqrt(3) - 1/2, x == 0, x == -1/2*I*sqrt(3) - 1/2]
sage: eq = a*x**2 == -sqrt(x)
sage: solve(eq,x,to_poly_solve=True)
[x == -sqrt(-sqrt(x)/a), x == sqrt(-sqrt(x)/a)]
</pre><p>
This is a simplification of an example a user posted on the Sage Facebook page.
</p>
en-usSagehttps://trac.sagemath.org/chrome/site/logo_sagemath_trac.png
https://trac.sagemath.org/ticket/14215
Trac 1.1.6kcrismanSun, 03 Mar 2013 01:26:50 GMT
https://trac.sagemath.org/ticket/14215#comment:1
https://trac.sagemath.org/ticket/14215#comment:1
<p>
This seems to be a general weakness in Maxima's solve; if someone wants to change this to a bug and not an enhancement, be my guest.
</p>
TicketkcrismanSun, 03 Mar 2013 01:29:03 GMT
https://trac.sagemath.org/ticket/14215#comment:2
https://trac.sagemath.org/ticket/14215#comment:2
<p>
The suggestion was made there that Sympy might be better at this. Is it? At least here it is giving answers - I don't think any are erroneous or missing, but I didn't check very hard, either.
</p>
<pre class="wiki">sage: from sympy import solve as ssolve
sage: ssolve(x-sqrt(x),x)
[1, 0]
sage: ssolve(x^2-sqrt(x),x)
[1, 0]
sage: ssolve(x^2+sqrt(x),x)
[-1/2 + 3**(1/2)*I/2, -1/2 - 3**(1/2)*I/2, 0]
sage: ssolve(a*x^2+sqrt(x),x)
[(-1/a)**(2/3),
0,
(-1/a)**(2/3)*(-1 - 3**(1/2)*I)/2,
(-1/a)**(2/3)*(-1 + 3**(1/2)*I)/2]
</pre><p>
Does anyone know whether sympy's solve capabilities is a strict superset of Maxima's? I assume not.
</p>
TicketjdemeyerTue, 13 Aug 2013 15:35:53 GMTmilestone changed
https://trac.sagemath.org/ticket/14215#comment:3
https://trac.sagemath.org/ticket/14215#comment:3
<ul>
<li><strong>milestone</strong>
changed from <em>sage-5.11</em> to <em>sage-5.12</em>
</li>
</ul>
Ticketvbraun_spamThu, 30 Jan 2014 21:20:52 GMTmilestone changed
https://trac.sagemath.org/ticket/14215#comment:4
https://trac.sagemath.org/ticket/14215#comment:4
<ul>
<li><strong>milestone</strong>
changed from <em>sage-6.1</em> to <em>sage-6.2</em>
</li>
</ul>
Ticketvbraun_spamTue, 06 May 2014 15:20:58 GMTmilestone changed
https://trac.sagemath.org/ticket/14215#comment:5
https://trac.sagemath.org/ticket/14215#comment:5
<ul>
<li><strong>milestone</strong>
changed from <em>sage-6.2</em> to <em>sage-6.3</em>
</li>
</ul>
Ticketvbraun_spamSun, 10 Aug 2014 16:51:03 GMTmilestone changed
https://trac.sagemath.org/ticket/14215#comment:6
https://trac.sagemath.org/ticket/14215#comment:6
<ul>
<li><strong>milestone</strong>
changed from <em>sage-6.3</em> to <em>sage-6.4</em>
</li>
</ul>
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