# Error: Unexpected values in bisection. (DifferentialEquations)

**URL:** <https://discourse.julialang.org/t/error-unexpected-values-in-bisection-differentialequations/45145>\
**Category:** Modelling & Simulations\
**Created:** [August 18, 2020, 7:00am UTC](https://discourse.julialang.org/t/error-unexpected-values-in-bisection-differentialequations/45145 "2020-08-18T07:00:51Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Lachlan-Bn](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lachlan-bn/32/17008_2.png) [@Lachlan-Bn](https://discourse.julialang.org/u/Lachlan-Bn)\
**Post date:** [August 18, 2020, 7:00am UTC](https://discourse.julialang.org/t/error-unexpected-values-in-bisection-differentialequations/45145/1 "2020-08-18T07:00:52Z")

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I’m encountering an error related to using BigFloats and a callback that terminates the integrator upon certain conditions. More specifically, julia throws the following error when calling `solve()` with the callback on a problem whose initial condition is of type `BigFloat`:

```julia
Unexpected values in bisection. Please report the error in DiffEqBase.
in include_string at base/loading.jl:1088
in top-level scope at threebody.jl:160
in at DiffEqBase/ypGPp/src/solve.jl:100
in #solve#460 at DiffEqBase/ypGPp/src/solve.jl:102 
in solve_up##kw at DiffEqBase/ypGPp/src/solve.jl:107 
in #solve_up#461 at DiffEqBase/ypGPp/src/solve.jl:114 
in solve_call##kw at DiffEqBase/ypGPp/src/solve.jl:65 
in #solve_call#457 at DiffEqBase/ypGPp/src/solve.jl:92
in at OrdinaryDiffEq/VPJBD/src/solve.jl:4
in #__solve#391 at OrdinaryDiffEq/VPJBD/src/solve.jl:5
in solve! at OrdinaryDiffEq/VPJBD/src/solve.jl:429
in loopfooter! at OrdinaryDiffEq/VPJBD/src/integrators/integrator_utils.jl:166 
in _loopfooter! at OrdinaryDiffEq/VPJBD/src/integrators/integrator_utils.jl:202
in handle_callbacks! at OrdinaryDiffEq/VPJBD/src/integrators/integrator_utils.jl:247
in find_first_continuous_callback at DiffEqBase/ypGPp/src/callbacks.jl:398 
in find_callback_time at DiffEqBase/ypGPp/src/callbacks.jl:730
in bisection at DiffEqBase/ypGPp/src/callbacks.jl:581 
in #bisection#410 at DiffEqBase/ypGPp/src/callbacks.jl:592
in error at base/error.jl:33

```

The integration succeeds when no callback is specified. The callback also performs as expected when the initial condition is Float64. The callback I am using is

```julia
import LinearAlgebra.norm

function condition(out,u,t,integrator)
  out[1] = norm(u[1:2])-Rsys
  out[2] = R1-norm(u[1:2]-P1) 
  out[3] = R2-norm(u[1:2]-P2) 
end

function affect!(integrator, event_index)
  terminate!(integrator)
end

```

My purposes necessitate higher precision than Float64, so I’d like to find a solution if possible. From the error message, I think the problem lies in detecting the zero crossing at high precision. Does this seem correct?

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<div class="post-metadata">

**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [August 18, 2020, 12:31pm UTC](https://discourse.julialang.org/t/error-unexpected-values-in-bisection-differentialequations/45145/2 "2020-08-18T12:31:36Z")

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Could you open an issue on DifferentialEquations.jl with enough code that we can run it? We’ll need to dig into this one.

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<div class="post-metadata">

**Author:** ![Lachlan-Bn](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lachlan-bn/32/17008_2.png) [@Lachlan-Bn](https://discourse.julialang.org/u/Lachlan-Bn)\
**Post date:** [August 18, 2020, 1:30pm UTC](https://discourse.julialang.org/t/error-unexpected-values-in-bisection-differentialequations/45145/3 "2020-08-18T13:30:50Z")

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Will do, thanks.

Edit: Done.

[https://github.com/SciML/DifferentialEquations.jl/issues/653](https://github.com/SciML/DifferentialEquations.jl/issues/653)

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<div class="post-metadata">

**Author:** ![Lachlan-Bn](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lachlan-bn/32/17008_2.png) [@Lachlan-Bn](https://discourse.julialang.org/u/Lachlan-Bn)\
**Post date:** [August 18, 2020, 3:08pm UTC](https://discourse.julialang.org/t/error-unexpected-values-in-bisection-differentialequations/45145/4 "2020-08-18T15:08:02Z")

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I’ve noticed that a `DiscreteCallback` works fine. The issue seems endemic to `ContinuousCallback`s.