Initial commit

1 files changed, 52 insertions, 0 deletions

diff --git a/Crosscorr.f b/Crosscorr.f
new file mode 100755
index 0000000..5e33d12
--- /dev/null
+++ b/Crosscorr.f
@@ -0,0 +1,52 @@
+
+      subroutine crosscorr (ishift,rxy,xcross,ycross,npx)
+c******************************************************************************
+c     This routine determines the correlation of array 'x' and array 'y',
+c     comparing array elements 'i' in 'x' with elements 'i+ishift';
+c     the number of points in each array is assumed to be equal.
+c******************************************************************************
+
+      implicit real*8 (a-h,o-z)
+      real*4 xcross(100000),ycross(100000)
+      real*8 xsum,ysum,xysum,x2sum,y2sum,covar,varx,vary
+      real*8 xx,yy
+
+
+      xsum = 0.
+      ysum = 0.
+      xysum = 0.
+      x2sum = 0.
+      y2sum = 0.
+      if (ishift .ge. 0) then
+         minpt = 1
+         maxpt = npx - ishift
+      else
+         minpt = iabs(ishift) + 1
+         maxpt = npx
+      endif
+
+
+      do 10 i=minpt,maxpt
+         xx = xcross(i)
+         yy = ycross(i+ishift)
+         xsum = xsum + xx
+         ysum = ysum + yy
+         xysum = xysum + xx*yy
+         x2sum = x2sum + xx*xx
+10       y2sum = y2sum + yy*yy
+
+
+      xn = real(maxpt - minpt + 1)
+      covar = xn*xysum - xsum*ysum
+      varx = dsqrt(xn*x2sum - xsum*xsum)
+      vary = dsqrt(xn*y2sum - ysum*ysum)
+      rxy = sngl(covar/(varx*vary))
+
+
+      return
+      end
+
+
+
+
+