Commodore PET User Manual page 211

Step 2: Vou must establish the maximum length of numeric input in
order to determine into how many segments to divide ail numeric input. For in-
$tance, if the maximum length of numeric input is 16 digits, Vou may divide large
numbers into two segments with a maximum of eight digits each. Any combina-
tion is permissible as long as no one segment exceeds a length of nine digits.
To keep our sample program simple, the maximum input length we will
allow is 16 digits, to be divided into high and low segments of eight digits each.
1
1
1
:~.....I
. . . . . . . . . . . ,
high
1
'-----'IL.-----'
8 digits
Il
8 digits
. .
.'..
.
For our sample program the divider point variable F is calculated ta one-ha If of the
larger input length.
First determine which input string is longer. The lengths of A$ and B$ are
assigned to variables X and Y respectively.
1000 X=LEN(A$):Y=LEN(B$)
Next. the lengths are compared. If X> y (Iength of A$ is larger than length of
BS)
then variable F. the divider variable. is set to one-half the length of X. But if X is
sm_11er than Y. the program drops through and Fis set ta one-ha If the length of Y.
1002 IF X>Y THEN F=X/2:GOTO 1006
1004 F=Y. . . . '2
ln this example, A$="1234567890123456" and B$="57943572"; le1's run
this through:
1000 X=LEN(A$):Y=LEN(B$)
X=16 Y=8
1002 1F ~':::::''r' THEN F=>::",'2: GOTO 1006
16> 8 true statement. therelore
F
=
16/2
F=8
program continues at line 1006
Once the value of F is set. the program continues at line 1006. Statement
1006 compares the value of F ta the integer value of F. If Fis larger than its integer
value, then F is assigned the value of its integer value plus 1. This is basically a
method of rounding F up to the nearest integer if F is a fractional number. For ex-
ample. if the value of F equals 7.5, line 1006 would ensure that F is an integer
number so that both A$ and B$ may be divided as easily and evenly as possible.
1006 IF F>INT(F) THEN F=INT(F)+l
117.5>7 then F = 7+1
F=8
198