# How to specify only certain inital conditions as parameters

**URL:** https://discourse.julialang.org/t/how-to-specify-only-certain-inital-conditions-as-parameters/78884
**Category:** New to Julia
**Tags:** differentialequation
**Created:** [April 1, 2022, 5:42pm UTC](https://discourse.julialang.org/t/how-to-specify-only-certain-inital-conditions-as-parameters/78884 "2022-04-01T17:42:33Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![xztt](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xztt/32/33843_2.png) [@xztt](https://discourse.julialang.org/u/xztt)
#### Post date: [April 1, 2022, 5:42pm UTC](https://discourse.julialang.org/t/how-to-specify-only-certain-inital-conditions-as-parameters/78884/1 "2022-04-01T17:42:33Z")

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Hi there

My questions resolves around the code below

```julia
function circ_local(x)
    _prob = remake(prob,u0=x[1:3],p=x[4:end])
    sol = solve(_prob,Tsit5(), reltol=1e-6, abstol=1e-6,saveat=savetime)
    [mean(sol[1,:]),maximum(sol[1,:]),maximum(sol[1,:])/mean(sol[1,:])]
end

```

Say `u0=[10,1,1]` I would only like to specify `u0[1]` as a parameter of the remake problem for which I will just this function to perform local sensitivity analysis.

My attempt looks like

```julia
function circ_local(x)
    _prob = remake(prob,u0[1,:]=x[1],p=x[2:end])
    sol = solve(_prob,Tsit5(), reltol=1e-6, abstol=1e-6,saveat=savetime)
    [mean(sol[1,:]),maximum(sol[1,:]),maximum(sol[1,:])/mean(sol[1,:])]
end

```

However this throws a syntax keyword argument.

Any help appreciated 🙂

Cheers,  
H

---

<div class="post-metadata">

### Author: ![Henrique\_Becker](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/henrique_becker/32/15443_2.png) [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)
#### Post date: [April 1, 2022, 10:06pm UTC](https://discourse.julialang.org/t/how-to-specify-only-certain-inital-conditions-as-parameters/78884/2 "2022-04-01T22:06:11Z")

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I do not believe there is a built-in way to get the default value and pass an argument computed based on it. It seems to me that the of author `remake` should have provided distinct parameters if makes sense to set them individually.