From 57f4ad36d001e78832d75de64dfc46c8d17c1c5f Mon Sep 17 00:00:00 2001
From: Yggdrasil <yggdrasil@massaman-labs.de>
Date: Fri, 24 Apr 2026 12:24:23 +0200
Subject: [PATCH] Seeds can now be externally set.

---
 event2_03.f | 57 +++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 44 insertions(+), 13 deletions(-)

diff --git a/event2_03.f b/event2_03.f
index bc2da73..ee6265a 100644
--- a/event2_03.f
+++ b/event2_03.f
@@ -24,6 +24,7 @@ C                                    - added CUTUP variable
 C   VERSION 0.4 - 23th April 2026 - separated hist ouput
 C                                 - added runcard input
 C                                 - allowed different bin sizes
+C                                 - seeds can now be externally set
 C
 C - NEV IS THE NUMBER OF EVENTS TO GENERATE
 C - EM IS THE TOTAL CENTRE-OF-MASS ENERGY
@@ -63,17 +64,7 @@ C
       DOUBLE PRECISION CFSUB,CASUB,TFSUB,GGSUB,QQSUB,QPSUB
       COMMON  /SUBCOM/ CFSUB,CASUB,TFSUB,GGSUB,QQSUB,QPSUB
       EXTERNAL USER
-C---PRINT OPENING MESSAGE
-      WRITE (*,'(/2A)')  ' This is EVENT2, a program for calculating',
-     $     ' jet quantities'
-      WRITE (*,'(2A)')   ' in e+e- annihilation to next-to-leading',
-     $     ' order in alpha_s'
-      WRITE (*,'(A)')    ' If you use this program, please reference:'
-      WRITE (*,'(2A)')   ' S.Catani & M.H.Seymour,',
-     $     ' Phys. Lett. B378 (1996) 287.'
-      WRITE (*,'(/A)')   ' Written by Mike Seymour, January 1996'
-      WRITE (*,'(A)')   ' Edited by Giorgio Chiurato, April 2026'
-      WRITE (*,'(A/)')   ' Version 0.4, April 2026'
+      CALL PRINTHEADER
       WRITE (*,'(A,I10)')' NEV=',NEV
 C---INITIALIZE CONSTANTS
       PI=ATAN(ONE)*4
@@ -191,12 +182,27 @@ C---TELL THE USER THAT THE EVENT IS COMPLETE
  1000   CALL USER(0,0,0,P,ZERO)
       ENDDO
       END
+C-----------------------------------------------------------------------
+      SUBROUTINE PRINTHEADER
+      IMPLICIT NONE 
+C---PRINT OPENING MESSAGE
+      WRITE (*,'(/2A)')  ' This is EVENT2, a program for calculating',
+     $      ' jet quantities'
+      WRITE (*,'(2A)')   ' in e+e- annihilation to next-to-leading',
+     $      ' order in alpha_s'
+      WRITE (*,'(A)')    ' If you use this program, please reference:'
+      WRITE (*,'(2A)')   ' S.Catani & M.H.Seymour,',
+     $      ' Phys. Lett. B378 (1996) 287.'
+      WRITE (*,'(/A)')   ' Written by Mike Seymour, January 1996'
+      WRITE (*,'(A)')   ' Edited by Giorgio Chiurato, April 2026'
+      WRITE (*,'(A/)')   ' Version 0.4, April 2026'
+      END
 C-----------------------------------------------------------------------
       SUBROUTINE READCARD
             implicit none
             integer            :: stat,n,nl,i,iline,ichar
-            character(2)       :: flag(1:2)
-            character(40)      :: val(1:2)
+            character(3)       :: flag(1:4)
+            character(40)      :: val(1:4)
             character(20)      :: fname
             character(72)      :: line
             character(12)      :: keys(20),settings(20)
@@ -213,8 +219,13 @@ C-----------------------------------------------------------------------
             DOUBLE PRECISION CL1,CL2,DL,TL,YL,EL,CH1,CH2,DH,TH,YH,EH
             DOUBLE PRECISION CBS1,CBS2,DBS,TBS,YBS,EBS
 
+            DOUBLE PRECISION ISEEDIN(2)
+
             CHARACTER*40 PATH
 
+            DATA fname/'card.input'/
+            DATA ISEEDIN/123450,678900/
+
             COMMON /PARAMS/ NFL,NEV,EM
             COMMON /CONCOM/ CF,CA,TR,PI,PISQ,HF,CUTOFF,CUTUP,
      $           CQ,FPAL2,ONF,NF,METYPE
@@ -237,22 +248,42 @@ C-----------------------------------------------------------------------
                   call getarg(4,val(2))
                   nl = 2
             endif
+            if (n.ge.6)then
+                  call getarg(5,flag(3))
+                  call getarg(6,val(3))
+                  nl = 3
+            endif
+            if (n.ge.8)then
+                  call getarg(7,flag(4))
+                  call getarg(8,val(4))
+                  nl = 4
+            endif
+
+C           TODO: need to add a proper info page and maybe change the input parameter handling.
 
             do i=1,nl
                   if (flag(i).eq.'-i')then
                         fname = val(i) 
                   elseif (flag(i).eq.'-o')then
                         PATH = val(i)
+                  elseif (flag(i).eq.'-sa') then
+                        read(val(i), *) ISEEDIN(1)
+                  elseif (flag(i).eq.'-sb') then
+                        read(val(i), *) ISEEDIN(2)
                   else 
+                        CALL PRINTHEADER
                         print *, 'Option ', flag(i), 
      $                  ' not recognized.'
+                        STOP "Exiting program..."
                   endif
             enddo
 
+            call RANGEN(0, ISEEDIN)
             call CREATEOUT(PATH)
 
             inquire(file=fname, exist=fexists)
             if (.not.fexists)then
+                  CALL PRINTHEADER
                   stop 'run card ' // trim(fname) // ' not found'
             endif