>
>
> Sorry to keep on here, but I've
> got three other related queries:
>
> (1) "solve?" gives me " solve(sin(x)==x,x,explicit_solutions=True)"
> as an example which returns an empty list of solutions.
> But x=0 surely counts as an explicit solution? I guess my
> interpretation of an empty list as "there cannot possibly be any
> solutions of this form"
> can't be right. Can we add a legal disclaimer along the lines of "an
> empty list does not guarantee the absence of solutions"?
>
>
Yes, you are right, we should do that. Currently in `x.solve?` (see below)
we have
Here is how the "explicit_solutions" keyword functions:
sage: solve(sin(x)==x,x)
[x == sin(x)]
sage: solve(sin(x)==x,x,explicit_solutions=True)
[]
sage: solve(x*sin(x)==x^2,x)
[x == 0, x == sin(x)]
sage: solve(x*sin(x)==x^2,x,explicit_solutions=True)
[x == 0]
which is indeed a little perplexing, but it did return all *known* (to
Maxima) explicit solutions... hmm.
> (2) Trying "solve(sin(x)==x,x,to_poly_solve=True)" gives me an
> unhelpful error message about indexing. What does this message mean
> and how can I mitigate it?
>
>
This is very unusual, but I see what happened. The code currently in place
does
sage: solve(abs(1-abs(1-x)) == 10, x)
[abs(abs(x - 1) - 1) == 10]
sage: _[0]
abs(abs(x - 1) - 1) == 10
sage: Y = _._maxima_().to_poly_solve(x).sage()
sage: Y
[[x == -10], [x == 12]]
where you need to index twice to get the solution. However,
sage: solve(sin(x)==x,x)
[x == sin(x)]
sage: _[0]
x == sin(x)
sage: Y = _._maxima_().to_poly_solve(x).sage()
sage: Y
[x == sin(x)]
And indeed we should catch this possibility. (My apologies for putting
this all here, but our Trac ticket server seems to be down.)
>
> (3) The docs say "For more details about solving a single equation,
> see the documentation for the single-expression solve()"
> Where can I find this documentation online?
>
>
There is a ticket for adding a lot of that to the main 'solve?' but Trac
seems to be down right now so I can't find it...
sage: x.solve?
should satisfy you for now, but it is something we are working on, you are
right.
Edit: Actually, I think that the stuff under
Here we demonstrate very basic use of the optional keywords for
a single expression to be solved::
is what you are looking for. There is still more we can do to make it
clear what we mean by that. For instance, explicit_solutions will be
ignored if you have more than one equation.
--
You received this message because you are subscribed to the Google Groups
"sage-support" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-support+unsubscr...@googlegroups.com.
To post to this group, send email to sage-support@googlegroups.com.
Visit this group at http://groups.google.com/group/sage-support?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.
