Hi Khalid, On 2018-03-02, saad khalid <saad1...@gmail.com> wrote: > I'm running this code: > find_root(e^(-2*x*1)-(1 - 4*x),-2,2) > > It returns > > 2.4011774461136836e-13 > > which is approximately 0. However, there should be another root around x = > -0.628. Why isn't it finding this root? > Is there any way I can make sure it finds all of them?
I suppose you know that in Python (which is the underlying language of SageMath), you can access the documenation of an object by putting a question mark after it. So, do sage: find_root? and you can read: Numerically find a root of "f" on the closed interval [a,b] (or [b,a]) if possible, where "f" is a function in the one variable. Note: this function only works in fixed (machine) precision, it is not possible to get arbitrary precision approximations with it. So, it says *a* root, not *all* roots. The solution returned above obviously is in the given intervall, and so SageMath's answer complies with the specification. If you want other solutions, you need to provide a smaller intervall: sage: f(x) = e^(-2*x*1)-(1-4*x) sage: find_root(f, -1,0) 0.0 sage: f(x=0) 0 --> one gets yet another solution, the intervall is still too large. Again smaller: sage: find_root(f, -1,-0.5) -0.6282156043130847 sage: f(x=_) -4.440892098500626e-16 And that was what you were looking for. Best regards, Simon -- 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 https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
