"only length-1 arrays can be converted to Python scalars" using scipy.optimize in Sage

I want to adjust the parameters of a model to a given set of data.

I'm trying to use scipy's function curve_fit in Sage, but I keep getting

TypeError: only length-1 arrays can be converted to Python scalars

Here´s my code:

from numpy import cos,exp,pif = lambda x: exp(  - 1 / cos(x)  )import numpy as npdef ang(time): return (time-12)*pi/12def temp(x,maxtemp):    cte=(273+maxtemp)/f(0)**(1/4)    if 6<x and x<18:        return float(cte*f(ang(x))**(1/4)-273)    else:        return -273lT=list(np.linspace(15,40,1+24*2))lT=[float(num) for num in lT]             #list of y dataltimes=np.linspace(0,24,6*24+1)[1:]ltimes=list(ltimes)                     #list of x datau0=lT[0]def u(time,maxtemp,k):                    #the function I want to fit to the data    def integ(t): return k*exp(k*t)*temp(t,maxtemp)    return exp(-k*time)*( numerical_integral(integ, 0, time)[0] + u0 )import scipy.optimize as optimizationprint optimization.curve_fit(u, ltimes, lT,[1000,0.0003])