# Nlsolve for find root for a system of ODE for an implicit runge kutta method

**URL:** <https://discourse.julialang.org/t/nlsolve-for-find-root-for-a-system-of-ode-for-an-implicit-runge-kutta-method/84349>\
**Category:** New to Julia\
**Tags:** package\
**Created:** [July 17, 2022, 8:23am UTC](https://discourse.julialang.org/t/nlsolve-for-find-root-for-a-system-of-ode-for-an-implicit-runge-kutta-method/84349 "2022-07-17T08:23:31Z")\
**Posts on this page:** 1\
**Showing post:** 22

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**Author:** ![John\_Gibson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/john_gibson/32/5321_2.png) [@John\_Gibson](https://discourse.julialang.org/u/John_Gibson)\
**Post date:** [July 18, 2022, 1:55pm UTC](https://discourse.julialang.org/t/nlsolve-for-find-root-for-a-system-of-ode-for-an-implicit-runge-kutta-method/84349/22 "2022-07-18T13:55:39Z")

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> [@Vick](#):
>
> I used your example: but the error says:
> 
> > ERROR: BoundsError: attempt to access 6-element Vector{Float64} at index [7]
> 
> And the location is in the f function at the “xcurr” on the first loop.

It’s pretty hard to guess what you did when you say “I used your example.” Did you try to run the code I provided by cutting and pasting it exactly as is? Did you try to run `nlsolve` using my `f!` and your `f`? Or something else? We need a complete minimum working example and explicit error messages to be able to help.

Please do read [Please read: make it easier to help you](https://discourse.julialang.org/t/please-read-make-it-easier-to-help-you/14757) and follow its recommendations.

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