Initial commit

2016-02-03 18:52:05 +00:00
commit d40505e161
507 changed files with 91383 additions and 0 deletions
@@ -0,0 +1,36 @@
+      FUNCTION dawson(x)
+      INTEGER NMAX
+      REAL dawson,x,H,A1,A2,A3
+      PARAMETER (NMAX=6,H=0.4,A1=2./3.,A2=0.4,A3=2./7.)
+      INTEGER i,init,n0
+      REAL d1,d2,e1,e2,sum,x2,xp,xx,c(NMAX)
+      SAVE init,c
+      DATA init/0/
+      if(init.eq.0)then
+        init=1
+        do 11 i=1,NMAX
+          c(i)=exp(-((2.*float(i)-1.)*H)**2)
+11      continue
+      endif
+      if(abs(x).lt.0.2)then
+        x2=x**2
+        dawson=x*(1.-A1*x2*(1.-A2*x2*(1.-A3*x2)))
+      else
+        xx=abs(x)
+        n0=2*nint(0.5*xx/H)
+        xp=xx-float(n0)*H
+        e1=exp(2.*xp*H)
+        e2=e1**2
+        d1=float(n0+1)
+        d2=d1-2.
+        sum=0.
+        do 12 i=1,NMAX
+          sum=sum+c(i)*(e1/d1+1./(d2*e1))
+          d1=d1+2.
+          d2=d2-2.
+          e1=e2*e1
+12      continue
+        dawson=0.5641895835*sign(exp(-xp**2),x)*sum
+      endif
+      return
+      END