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R1448/ChiBenchmark/lenstoolchi/utils/smooth.f
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smooth.f
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c=======================================================================
c
subroutine smooth(small,nxin,nyin,array,nx,ny,npix,iw)
c
c Convolves an nxin by nyin image with a gaussian of width npix pixels,
c writing the result to a nx by ny array.
c iw = 0 -> bilinear interpolation (iw = 2 -> silent)
c iw = 1 -> nearest neighbours interp. (iw = 3 -> silent)
c
implicit none
c
integer nxin,nyin,nx,ny,nxout,nyout
integer npix,iw
real small(nxin,nyin),large(nx,ny)
real array(nx,ny)
real value
real barea,bfwhm
real beam(nx,ny),work(2*nx)
real xp(nx),yp(ny)
complex beamfft(nx,ny),wkspce(nx*ny),wkspce2(nx*ny)
logical verbose
c
integer i,j,ndim,nn(2),n
integer job,iform
c
c-----------------------------------------------------------------------
c
c initialise variables
nxout = nx
nyout = ny
bfwhm = float(npix)
if (iw.eq.2) then
iw = 0
verbose = .false.
elseif (iw.eq.3) then
iw = 1
verbose = .false.
else
verbose = .true.
endif
c regrid array
do i=1,nx
do j=1,ny
large(i,j) = 0.0
enddo
enddo
do i=1,nxin
do j=1,nyin
large(i,j) = small(i,j)
enddo
enddo
ndim=2
nn(1)=nx
nn(2)=ny
if (verbose) write(*,*) 'Regridding array ... '
call regrid(nx,ny,nxin,nyin,nxout,nyout,large,array,xp,yp,iw)
c ... make beam
if (verbose) write(*,*) 'Making Gaussian ... '
call makebeam(beam,nx,ny,nxout,nyout,barea,bfwhm)
c ... make beam FFT
n=0
do i=1,nxout
do j=1,nyout
n=n+1
wkspce(n)=cmplx(beam(i,j),0.)
end do
end do
job=-1 ! forward transform (-ve exponential)
iform=0 ! data are real
call cheqboard(wkspce,nxout,nyout)
call fourt(wkspce,nn,ndim,job,iform,work)
call cheqboard(wkspce,nxout,nyout)
n=0
do i=1,nxout
do j=1,nyout
n=n+1
beamfft(i,j)=wkspce(n)
end do
end do
c ... convolve maps with beam
if (verbose) write(*,*) 'Convolving map with Gaussian ...'
n=0
do i=1,nxout
do j=1,nyout
n=n+1
value=array(i,j)
wkspce(n)=cmplx(value,0.)
end do
end do
c .. FFT sky
job=-1 ! forward transform (-ve exponential)
iform=0 ! data are real
call cheqboard(wkspce,nxout,nyout)
call fourt(wkspce,nn,ndim,job,iform,work)
call cheqboard(wkspce,nxout,nyout)
c ... multiply FFT(sky) by beamfft at given frequency
n=0
do i=1,nxout
do j=1,nyout
n=n+1
wkspce2(n)=wkspce(n)*beamfft(i,j)
end do
end do
c ... inverse FFT to obtain convolved sky at given frequency
job=1 ! backward transform (+ve exponential)
iform=1 ! data are complex
call cheqboard(wkspce2,nxout,nyout)
call fourt(wkspce2,nn,ndim,job,iform,work)
call cheqboard(wkspce2,nxout,nyout)
c ... normalise FFT and copy to array
n=0
do i=1,nxout
do j=1,nyout
n=n+1
array(i,j)=real(wkspce2(n))/real(nx*ny)/barea
end do
end do
999 return
end
c-----*-----------------------------------------------------------------
subroutine cheqboard(array,nx,ny)
implicit none
integer nx,ny
complex array(nx,ny)
integer i,j
do i=1,nx-1,2
do j=1,ny-1,2
array(i+1,j)=-array(i+1,j)
array(i,j+1)=-array(i,j+1)
end do
end do
end
c-----*-----------------------------------------------------------------
subroutine makebeam(beam,nx,ny,nxout,nyout,beamarea,fwhm)
implicit none
integer nx,ny,nxout,nyout
real beam(nx,ny),beamarea,fwhm
integer i,j
real sigma,dist
integer centrex,centrey
do i=1,nx
do j=1,ny
beam(i,j)=0.
end do
end do
centrex = nxout/2 + 1
centrey = nyout/2 + 1
sigma=fwhm/(2.*sqrt(2.*log(2.)))
beamarea=0.
do i=1,nxout
do j=1,nyout
dist=sqrt(float(i-centrex)**2+float(j-centrey)**2)
beam(i,j)=exp(-dist**2 / (2*sigma**2))
beamarea=beamarea+beam(i,j)
end do
end do
return
end
c-----*-----------------------------------------------------------------
include "rfft.f"
include "regrid.f"
c-----*-----------------------------------------------------------------
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