Hello,

I have a small system of 2 differential equations whose `@variables`

are `N1`

and `N2`

, with 3 `@parameters`

`a, b, c`

. I have evolution data (experimental measurements) for the variable `N1`

only, named (time, data).

I would like to use `DiffEqParamEstim.jl`

to fit my model on my data and to estimate the optimal `a,b,c`

parameters.

How can I change the following cost function (and in particular the L2Loss I think) to fit the data only on `N1`

and not on `N2`

?

```
cost_function = build_loss_objective(prob, Tsit5(), L2Loss(time, data),
Optimization.AutoForwardDiff(),
maxiters=10000,verbose=false)
optprob = Optimization.OptimizationProblem(cost_function, [0.0005, 0.009, 0.09])
result_bfgs = solve(optprob, BFGS())
```

Tanks !

fdekerm