Dear list,
This is a suggestion to improve the range of expressions over which the
implicit_plot code works. I've tried to do this myself but lack the
technical programming skill in LISP to implement it.
Working from examples:
implicit_plot(x-y, [x,-4,4], [y,-4,4]);
is fine but
implicit_plot((x-y)^2, [x,-4,4], [y,-4,4]);
returns -1. In fact the graphs of these two expressions are identical. In
general if
p=a*b
then the implicit plot of p=0 is simply the union of the implicit plots of
a=0 and b=0.
Hence, would it be possible for implicit_plot to
(1) attempt to factor the expression (eg using factor)
(2) loop across distinct factors, applying the current "implicit_plot" to
each of these.
(3) Generate a graph as the superposition of the components found by (2)
(An option for a separate colour for each would of course be nice, but not
essential)
This would also have the advantage of giving "sharper corners" to implicit
plots such as x^2-y^2=0, which traditionally do not fair well by implicit
plot routines.
Regards,
Chris Sangwin