A-M baby

Task/Loops-Break/Fortran/loops-break-1.f

@@ -0,0 +1,17 @@
+program Example
+  implicit none
+
+  real :: r
+  integer :: a, b
+
+  do
+     call random_number(r)
+     a = int(r * 20)
+     write(*,*) a
+     if (a == 10) exit
+     call random_number(r)
+     b = int(r * 20)
+     write(*,*) b
+  end do
+
+end program Example

Task/Loops-Break/Fortran/loops-break-2.f

@@ -0,0 +1,69 @@
+      PROGRAM LOOPBREAK
+        INTEGER I, RNDINT
+
+C       It doesn't matter what number you put here.
+        CALL SDRAND(123)
+
+C       Because FORTRAN 77 semantically lacks many loop structures, we
+C       have to use GOTO statements to do the same thing.
+   10   CONTINUE
+C         Print a random number.
+          I = RNDINT(0, 19)
+          WRITE (*,*) I
+
+C         If the random number is ten, break (i.e. skip to after the end
+C         of the "loop").
+          IF (I .EQ. 10) GOTO 20
+
+C         Otherwise, print a second random number.
+          I = RNDINT(0, 19)
+          WRITE (*,*) I
+
+C         This is the end of our "loop," meaning we jump back to the
+C         beginning again.
+          GOTO 10
+
+   20   CONTINUE
+
+        STOP
+      END
+
+C FORTRAN 77 does not have come with a random number generator, but it
+C is easy enough to type "fortran 77 random number generator" into your
+C preferred search engine and to copy and paste what you find. The
+C following code is a slightly-modified version of:
+C
+C     http://www.tat.physik.uni-tuebingen.de/
+C         ~kley/lehre/ftn77/tutorial/subprograms.html
+      SUBROUTINE SDRAND (IRSEED)
+        COMMON  /SEED/ UTSEED, IRFRST
+        UTSEED = IRSEED
+        IRFRST = 0
+        RETURN
+      END
+      INTEGER FUNCTION RNDINT (IFROM, ITO)
+        INTEGER IFROM, ITO
+        PARAMETER (MPLIER=16807, MODLUS=2147483647,                     &
+     &              MOBYMP=127773, MOMDMP=2836)
+        COMMON  /SEED/ UTSEED, IRFRST
+        INTEGER HVLUE, LVLUE, TESTV, NEXTN
+        SAVE    NEXTN
+        IF (IRFRST .EQ. 0) THEN
+          NEXTN = UTSEED
+          IRFRST = 1
+        ENDIF
+        HVLUE = NEXTN / MOBYMP
+        LVLUE = MOD(NEXTN, MOBYMP)
+        TESTV = MPLIER*LVLUE - MOMDMP*HVLUE
+        IF (TESTV .GT. 0) THEN
+          NEXTN = TESTV
+        ELSE
+          NEXTN = TESTV + MODLUS
+        ENDIF
+        IF (NEXTN .GE. 0) THEN
+          RNDINT = MOD(MOD(NEXTN, MODLUS), ITO - IFROM + 1) + IFROM
+        ELSE
+          RNDINT = MOD(MOD(NEXTN, MODLUS), ITO - IFROM + 1) + ITO + 1
+        ENDIF
+        RETURN
+      END