scipy: BUG: dblquad and args kwarg

Describe your issue.

There is a bug with scipy.dblquad that seems to be involved with using the args kwarg. The example below is the integral of a 2D Normal distribution, which should be unity. I am using the args kwarg to pass the coords of the center of the Normal. Note that the boundary of the integral is also using the same variable that are passed in args (although I don’t know why that might matter).

Reproducing Code Example

< import numpy as np; from scipy.integrate import dblquad
< sig = 1.3; x0=5.; y0=-3.;
< g = lambda x,y,xc,yc : (1/(2*np.pi*sig*sig))*np.exp(- ((x-xc)**2 + (y-yc)**2)/(2*sig*sig) )
< print([g(x0,y0,x0,y0), g(x0+1,y0+1,x0,y0)])
[0.09417452253958304, 0.05211400420209555]
< print([g(x0,y0,x0-5*sig,y0), g(x0+5*sig,y0,x0,y0)])
[3.509557831511321e-07, 3.509557831511321e-07]

< dblquad(g,x0-5*sig,x0+5*sig,y0-5*sig,y0+5*sig,args=(x0,y0))
> (0.015445922091068943, 6.2668582074865746e-09)
this answer is not close enough to unity for my taste.

Error message

no error message, just the wrong answer!

SciPy/NumPy/Python version information

np 1.16.2 scipy 1.2.1