Thanks very much for the example. I wasn't aware of the removeO() method. On Tuesday, August 18, 2020 at 5:21:04 PM UTC-4 [email protected] wrote:
> 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/db34ee08-0bb2-4e7a-a658-5a079d16c88bn%40googlegroups.com.
