desires. The JCL and control cards for accomplishing this are shown in
Figure 7.
 This strategy involves a two step job. The first step executes an
 IBM utility program called IEBGENER which merely copies the problem data
 onto a disk file. The second step is the LCRAND program which reads the
 problem, makes any indicated changes, and solves it. It will continue to
 do this as many times as the user indicates.
 In Figure 7, line 1 indicates the program to execute. Lines 2
 through 7 define the data sets necessary for IEBGENER. Line 2 is the
 print data set; line 3 defines SYSIN as a Dummy Data Set which means we
 are not using it; lines 4, 5, and 6 create the scratch disk data set
 which is the output file for our copy operation; and line 7 defines our
 input data set coming from cards. Lines 8 through 13 and the indicated
 data are exactly the same as lines 7 through 12 in the sample program at
 the beginning of Section 3. They define the problem in its initial or
 standard form. Line 14 is the "EOF" or ("end of file") statement which
 indicates the end of the problem file, and directs the LCRAND program to
 return to sending from the card input stream for the LCRAND program,
 (The data set defined by line 20 and consisting of lines 21 through 29).
 This latter data set can be thought of as a control program in this
 context.
 After the copy operation is performed, the LCRAND is executed as
indicated in line 15. Lines 16, 17, 18 and 20 are as defined in Section 3.
Line 19 defines the data set created in step 1 (by TEBGENER) so that
LCRAND knows where to find the problem. Line 21 is the standard BEGIN
statement which initializes program parameters. The "TAPE" statement in
line 22 causes the LCRAND to read the problem from our scratch data set
(FORTRAN unit 11). Then the problem is solved (unchanged), as indicated
in line 23. Lines 24 and 25 begin the same sequence, only this time the
problem is changed by ALTERA before SOLVE in line 28. This sequence of
statements consisting of lines 24 through 28 is then repeated for each
change that is desired. Note that these coefficient changes are not
cumulative. With each new "BEGIN"-"TAPE" sequence, the data returns to
the initial problem structure. Finally, the program terminates when it
reaches the exit statement in line 29.
 The control ALTERB could be used in place of, or in addition to, the