A-M baby

Task/Loops-Nested/Fortran/loops-nested-1.f

@@ -0,0 +1,76 @@
+      PROGRAM LOOPNESTED
+        INTEGER A, I, J, RNDINT
+
+C       Build a two-dimensional twenty-by-twenty array.
+        DIMENSION A(20,20)
+
+C       It doesn't matter what number you put here.
+        CALL SDRAND(123)
+
+C       Fill the array with random numbers.
+        DO 20 I = 1, 20
+          DO 10 J = 1, 20
+            A(I, J) = RNDINT(1, 20)
+   10     CONTINUE
+   20   CONTINUE
+
+C       Print the numbers.
+        DO 40 I = 1, 20
+          DO 30 J = 1, 20
+            WRITE (*,5000) I, J, A(I, J)
+
+C           If this number is twenty, break out of both loops.
+            IF (A(I, J) .EQ. 20) GOTO 50
+   30     CONTINUE
+   40   CONTINUE
+
+C       If we had gone to 40, the DO loop would have continued. You can
+C       label STOP instead of adding another CONTINUE, but it is good
+C       form to only label CONTINUE statements as much as possible.
+   50   CONTINUE
+        STOP
+
+C       Print the value so that it looks like one of those C arrays that
+C       makes everybody so comfortable.
+ 5000   FORMAT('A[', I2, '][', I2, '] is ', I2)
+      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

Task/Loops-Nested/Fortran/loops-nested-2.f

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+program Example
+  implicit none
+
+  real :: ra(5,10)
+  integer :: ia(5,10)
+  integer :: i, j
+
+  call random_number(ra)
+  ia = int(ra * 20.0) + 1
+
+outer: do i = 1, size(ia, 1)
+         do j = 1, size(ia, 2)
+           write(*, "(i3)", advance="no") ia(i,j)
+           if (ia(i,j) == 20) exit outer
+         end do
+         write(*,*)
+       end do outer
+
+end program Example