#12922: Implicit derivative
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Reporter: mmarco | Owner: burcin
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.10
Component: calculus | Resolution:
Keywords: implicit derivative | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Miguel Marco | Merged in:
Dependencies: | Stopgaps:
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Comment (by burcin):
Replying to [comment:10 mmarco]:
> {{{
> sage: implicit_derivative(y,x,x^2+y^2-1)
> -D[0](f)(symbol160, y(symbol160))/D[1](f)(symbol160, y(symbol160))
> }}}
It looks like the substitution doesn't work at some point.
Looking at the code...
The calls `y.diff(x,i+1)(x=x)` and `f.diff(x,i,yy,j)(x=x,yy=y)` rely on
the name of the variable. You should use a dictionary argument to
`.subs()`.
BTW, the `subs_expr()` method will go away at some point. Why not just use
`.subs()` everywhere?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12922#comment:11>
Sage <http://www.sagemath.org>
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