# Parameter Estimate Problem

**URL:** <https://discourse.julialang.org/t/parameter-estimate-problem/20695>\
**Category:** Optimization (Mathematical)\
**Tags:** diffeq\
**Created:** [February 12, 2019, 7:49am UTC](https://discourse.julialang.org/t/parameter-estimate-problem/20695 "2019-02-12T07:49:42Z")\
**Posts on this page:** 1\
**Showing post:** 7

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**Author:** ![hzgzh](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hzgzh/32/6596_2.png) [@hzgzh](https://discourse.julialang.org/u/hzgzh)\
**Post date:** [February 14, 2019, 7:37am UTC](https://discourse.julialang.org/t/parameter-estimate-problem/20695/7 "2019-02-14T07:37:53Z")

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I ref this “[Handling Instability When Solving ODE Problems - #5 by ChrisRackauckas](https://discourse.julialang.org/t/handling-instability-when-solving-ode-problems/9019/5)”,Thanks.  
But I found in solver option ’ \* `d_discontinuities:` Denotes locations of discontinuities in low order derivatives. This will force FSAL algorithms which assume derivative continuity to re-evaluate the derivatives at the point of discontinuity. The default is `[]` .',can you give some example how to use this d\_discontinuities

 ![image](https://global.discourse-cdn.com/julialang/original/3X/e/5/e5bb82bcacd1470d219d4236c00629308358d655.png)

add these code

```julia
function condition(u,t,integrator)
        t-t_discontinue
    end
    
    function affect!(integrator)
        println("u1=",integrator.u[1],"t=",integrator.t)
    end

    cb = ContinuousCallback(condition,affect!,save_positions=(false,false))
'''
```

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