subroutine pdist(np,x,scale,nbins,y)
c     calculate distribution function for x, store in y
c     np is the number of points in x
c     mx is the memory spacing for the x-array
c     distribution will be calculated for the range from -scale to + scale
c     nbins is the number of bins
c     my is the memory spacing for the y-array
c--------------------------------------------------------------------------
c
      include 'param_sz.h'
      include 'ucom.h'
c
      dimension x(2,imaa),y(2,imaa)
c--------------------------------------------------------------------------
c*
      dx=2.*scale/(nbins-1)
      rn=1./np
      do 10 i=1,nbins
      y(1,i)=0.
  10  continue
      do 20 i=1,np
      j=(x(1,i)+scale)/dx + 1.5
      if(j.lt.1)j=1
      if(j.gt.nbins)go to 20
      y(1,j)=y(1,j)+rn
  20  continue
      do 30 i=2,nbins
      y(1,i)=y(1,i-1)+y(1,i)
  30  continue 
      return
      end
c++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*