Error while interpolating OCV data

[suryankolluri]

Hello,

I am trying to specify positive electrode open circuit potential as data followed by interpolation command as suggested in #1848 . But, Casadi linear solver is failing. But, when I use it's corresponding expression, it just works good. Can someone help me how to use OCV data instead of expression because it is not possible to fit data to an expression in all the cases.

I having the following error message
psetup failed: .../casadi/interfaces/sundials/idas_interface.cpp:852: Linear solve failed

This is how I added OCV data
import numpy as np
ocppos = np.genfromtxt('nmc_OCP.csv',delimiter=',')
def OCV_pos(sto):
global ocppos
sto_ref = ocppos[:,0]
ocpp_ref =ocppos[:,1]
Up = pb.Interpolant(sto_ref, ocpp_ref, sto)
return Up

Also attaching the code(change the extension from .txt to .py) for the reference. any inputs will be very helpful.

Thanks,
Surya

P2D_Pybamm_inbuiltPDE_ver5.txt
nmc_OCP.csv

[suryankolluri]

I was able to resolve the issue by specifying the interpolator. When I use the following command it works
Up = pb.Interpolant(sto_ref, ocpp_ref, sto,interpolator='linear')