raise LinAlgError('Matrix is singular.')

LinAlgError: Matrix is singular.

#2-d interpolation
import numpy as np
from scipy import interpolate
import pandas as pd
#Read the Dataset from Excel File
dataset=pd.read_excel('Messwerte_FIBRE.xlsx')
dataset=dataset.drop([0])
index1=[1]
index4=[9]
x1=dataset.iloc[:, index1]
y=dataset.iloc[:, index4]
#converting string into array
x1np=np.array(x1,dtype=float)
ynp=np.array(y,dtype=float)
def func(x1np,x2np):
    return (x1np+x2np)*np.exp(-5.0*(x1np**2 + x2np**2))
fvals = func(x1np,ynp)
newfunc = interpolate.Rbf(x1np, ynp, fvals,function='thin-plate')