Sage: Ticket #22149: solve can't handle certain multi-equation settings
https://trac.sagemath.org/ticket/22149
<p>
See <a class="ext-link" href="https://ask.sagemath.org/question/36205/cant-solve-equation-with-abs-in-the-terms/"><span class="icon"></span>this ask.sagemath question</a>. Basically, at least in certain situations involving <code>abs()</code>, you
</p>
<pre class="wiki">var('x y a b')
f=[1+y-a*abs_symbolic(x)==x, b*x==y]; f
solve(f, [x, y])
</pre><p>
gives boom, or more precisely
</p>
<pre class="wiki">TypeError: cannot coerce arguments: no canonical coercion from <type 'list'> to Symbolic Ring
</pre><p>
since it somehow is trying to make this into one object. But
</p>
<pre class="wiki">assume(x>0)
solve(f, [x, y])
</pre><p>
gives not boom. So somehow our code for recognizing when we have a system of equations isn't working right in the first case. Note that
</p>
<pre class="wiki">var('x y a b')
f=[1+y-a*x==x, b*x==y]
solve(f,[x,y]
</pre><p>
apparently works fine.
</p>
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https://trac.sagemath.org/ticket/22149
Trac 1.1.6