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sqrnewt.cbl

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+       IDENTIFICATION DIVISION.
+      * A rewrite of a fortran program that is rewrite of a REXX script
+      * to find the square root of a number
+
+       PROGRAM-ID.    SQRNEWT.
+       AUTHOR.        Wayne.
+
+       DATA DIVISION.
+       WORKING-STORAGE SECTION.
+       01 WORK-AREA.
+           05 MAX-ITER      PIC  9(3)       VALUE  100.
+           05  ITER         PIC  9(3).
+           05  TOL          PIC  9(3)V9(12)  VALUE  0.0000000001.
+           05  RR           PIC S9(3)V9(12).
+           05  R            PIC S9(3)V9(12).
+           05  N            PIC S9(3)V9(12).
+           05  N-TEXT       PIC X(15).
+           05  DIS-RESULTS  PIC Z(3).9(12).
+
+       PROCEDURE DIVISION.
+           DISPLAY "Enter a 3 digit value <> 0:"
+      *    ACCEPT N FROM PARMS
+      *    MOVE 4 TO N
+           ACCEPT N-TEXT
+
+           PERFORM VALID-INPUT
+           STOP RUN.
+
+      *    Validate the input
+      *    If less than 0 ie negative, make it positive
+      *    If 0 then drop out
+       VALID-INPUT.
+           INSPECT N-TEXT REPLACING ALL "," BY "."
+           COMPUTE N = FUNCTION NUMVAL(N-TEXT)
+      *    DISPLAY N
+
+           IF N LESS THAN ZERO THEN
+             COMPUTE N = N * (- 1)
+             DISPLAY "CORRECTED FOR NEGATIVE VALUE"
+           END-IF.
+
+           IF N NOT EQUAL ZERO THEN
+             PERFORM FIND-SQRROOT
+           ELSE
+             DISPLAY "CANNOT BE ZERO"
+           END-IF.
+       END-VALID-INPUT.
+
+      *    Find the SQR Root of a number
+       FIND-SQRROOT.
+           MOVE 0 to ITER
+           MOVE 1 to R
+
+           PERFORM UNTIL ITER GREATER OR EQUAL MAX-ITER
+             COMPUTE ITER = ITER + 1
+             COMPUTE RR = (N / R + R) / 2
+
+             IF (FUNCTION ABS(RR - R) <= TOL) THEN
+               EXIT PERFORM
+             END-IF
+
+             MOVE RR TO R
+           END-PERFORM
+
+           MOVE RR TO DIS-RESULTS
+           DISPLAY DIS-RESULTS.
+       END-FIND-SQRROOT.
+