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Flags – HP 32SII User Manual

Page 199

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Programming

Techniques

13–9

File name 32sii-Manual-E-0424
Printed Date : 2003/4/24 Size : 17.7 x 25.2 cm

!

º

<¸@

Tests to see if the correction is significant.

!

!

!

Goes back to start of loop if correction is
significant. Continues if correction is not
significant.

!

%

!

#$

%

Displays the calculated value of X.

Line T09 calculates the correction for X

guess

. Line T13 compares the absolute

value of the calculated correction with 0.0001. If the value is less than
0.0001 ("Do If True"), the program executes line T14; if the value is equal to
or greater than 0.0001, the program skips to line T15.

Flags

A flag is an indicator of status. It is either set (true) or clear (false). Testing a
flag
is another conditional test that follows the "Do if true" rule: program
execution proceeds directly if the tested flag is set, and skips one line if the
flag is clear.

Meanings of Flags

The HP 32SII has 12 flags, numbered 0 through 11. All flags can be set.,
cleared, and tested from the keyboard or by a program instruction. The
default state of all 12 flags is clear. The three–key memory clearing operation
described in appendix B clears all flags. Flags are not affected by

z

b

{

} {

&

}.

Flags 0, 1, 2, 3, and 4 have no preassigned meanings. That is, their

states will mean whatever you define it to mean in a given program. (See
the example below.)

Flag 5, when set, will interrupt a program when an overflow occurs

within the program, displaying

#$

and

£

. An overflow occurs

when a result exceeds the largest number that the calculator can handle.
The largest possible number is substituted for the overflow result. If flag 5
is clear, a program with an overflow is not interrupted, though

#$

is displayed briefly when the program eventually stops.

Flag 6 is automatically set by the calculator any time an overflow occurs

(although you can also set flag 6 yourself). It has no effect, but can be