If I understand the references correctly, you'd want to replace instances of a and b in the expression with b/a, replace that with a single variable like x, then do a series expansion and remove higher order x terms. There isn't anything in SymPy that automates this in one step but you can get a lot of it automatically with subs() and series(). The hard part is that in some of the examples you may have to perform this on subexpressions rather than the whole expression.
For example, one of the examples you linked to is 1/(b*(b + a)) = 1/(b*a) if a >> b. >>> expr = 1/(b*(a + b)) >>> # Set x = b/a >>> expr.subs(a, b/x).cancel() x/(b**2*x + b**2) >>> # Expand as a series up to O(x**2) >>> expr.subs(a, b/x).cancel().series(x, n=2) x/b**2 + O(x**2) >>> # Remove the O() term and substitute back >>> expr.subs(a, b/x).cancel().series(x, n=2).removeO().subs(x, b/a) 1/(a*b) Aaron Meurer On Sat, Aug 15, 2020 at 2:07 PM Ben <[email protected]> wrote: > > Hello, > > I'm attempting to translate Latex into SymPy and am seeking guidance on how > to handle the notation of "much greater than." > > For example, "a + b = c" is replaced by "a = c" under the condition "b << a". > How would that be represented in Sympy? > > I like the explanation of ">>" provided in this StackOverflow answer, so > there is some deeper meaning to the notation. However, that doesn't indicate > what the appropriate representation in SymPy would be. > > For comparison with other Computer Algebra Systems, I'm not able to find the > concept in Sage documentation. I did find this post on Mathematica. > > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/446b0334-0fc0-48ad-802a-3ac7e3225667n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAKgW%3D6Kb7V%3DLgveunz5PKss-kd2qBQZSg%3DkJdNayBRb2qQ142A%40mail.gmail.com.
