def _buildvgrid(self,R,phi,nsigma,t,sigmaR1,sigmaT1,meanvR,meanvT,
                    gridpoints,print_progress,integrate_method,deriv):
        """Internal function to grid the vDF at a given location"""
        out= evolveddiskdfGrid()
        out.sigmaR1= sigmaR1
        out.sigmaT1= sigmaT1
        out.meanvR= meanvR
        out.meanvT= meanvT
        out.vRgrid= nu.linspace(meanvR-nsigma*sigmaR1,meanvR+nsigma*sigmaR1,
                                gridpoints)
        out.vTgrid= nu.linspace(meanvT-nsigma*sigmaT1,meanvT+nsigma*sigmaT1,
                                gridpoints)
        if isinstance(t,(list,nu.ndarray)):
            nt= len(t)
            out.df= nu.zeros((gridpoints,gridpoints,nt))
            for ii in range(gridpoints):
                for jj in range(gridpoints-1,-1,-1):#Reverse, so we get the peak before we get to the extreme lags NOT NECESSARY
                    if print_progress: #pragma: no cover
                        sys.stdout.write('\r'+"Velocity gridpoint %i out of %i" % \
                                             (jj+ii*gridpoints+1,gridpoints*gridpoints))
                        sys.stdout.flush()
                    thiso= Orbit([R,out.vRgrid[ii],out.vTgrid[jj],phi])
                    out.df[ii,jj,:]= self(thiso,nu.array(t).flatten(),
                                          integrate_method=integrate_method,
                                          deriv=deriv,use_physical=False)
                    out.df[ii,jj,nu.isnan(out.df[ii,jj,:])]= 0. #BOVY: for now
            if print_progress: sys.stdout.write('\n') #pragma: no cover
        else:
            out.df= nu.zeros((gridpoints,gridpoints))
            for ii in range(gridpoints):
                for jj in range(gridpoints):
                    if print_progress: #pragma: no cover
                        sys.stdout.write('\r'+"Velocity gridpoint %i out of %i" % \
                                             (jj+ii*gridpoints+1,gridpoints*gridpoints))
                        sys.stdout.flush()
                    thiso= Orbit([R,out.vRgrid[ii],out.vTgrid[jj],phi])
                    out.df[ii,jj]= self(thiso,t,
                                        integrate_method=integrate_method,
                                        deriv=deriv,use_physical=False)
                    if nu.isnan(out.df[ii,jj]): out.df[ii,jj]= 0. #BOVY: for now
            if print_progress: sys.stdout.write('\n') #pragma: no cover
        return out
Internal function to grid the vDF at a given location