# [SciPy-user] Fitting a function, which is an integral

Robert Kern robert.kern@gmail....
Fri Jan 23 16:20:27 CST 2009

```On Fri, Jan 23, 2009 at 16:00, Lukasz Klopotowski
<lukasz.klopotowski@ifpan.edu.pl> wrote:
> Hi!
>
> I need to fit a function, which is an integral. For example, I do:
>  >>> from scipy import *
>  >>> from scipy import integrate
>  >>> from scipy import optimize
>  >>> def pfun(p):
> ...     def fun(x):
> ...         return p[0]+p[1]*x
> ...     return fun
> ...
>  >>> def caleczka(p,x):
> ...     return integrate.quad(pfun(p),0,x)
> ...
>  >>> def errcal(p,x,y):
> ...     return caleczka(p,x)-y
> ...
>
> and after:
>
>  >>> optimize.leastsq(errcal, [1,2], (ix, iy))
>
> I get:
>
> Traceback (most recent call last):
>  File "<interactive input>", line 1, in <module>
>  File "C:\Python25\Lib\site-packages\scipy\optimize\minpack.py", line
> 266, in leastsq
>    m = check_func(func,x0,args,n)[0]
>  File "C:\Python25\Lib\site-packages\scipy\optimize\minpack.py", line
> 12, in check_func
>    res = atleast_1d(thefunc(*((x0[:numinputs],)+args)))
>  File "<interactive input>", line 2, in errcal
>  File "<interactive input>", line 2, in caleczka
>  File "C:\Python25\Lib\site-packages\scipy\integrate\quadpack.py", line
> 185, in quad
>    retval = _quad(func,a,b,args,full_output,epsabs,epsrel,limit,points)
>  File "C:\Python25\Lib\site-packages\scipy\integrate\quadpack.py", line
> 233, in _quad
>    if (b != Inf and a != -Inf):
> ValueError: The truth value of an array with more than one element is
> ambiguous. Use a.any() or a.all()
>
> Could someone take a look and point me in the right direction?

The limit arguments to integrate.quad() cannot be arrays. They must be scalars.

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
-- Umberto Eco
```

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