Radio Shack TRS-80 - Page 158

where
the triangle
looks
like this:
A
=
3
B
=
4
Okay.
That's not too
grim.
So
let's
write
a program to
find the value of L,
when A
=
3
and
B
=
4. If we
had
the built-in
square
root function
(which we
don't),
our
program
might
look
like this
:
10
REM
*
SQUARE
ROOT
SOLUTION WITH
SUBROUTINE
*
20 IN.
"THE LENGTH OF
SIDE
A
=
";A
30 IN. "THE LENGTH
OF SIDE
B
=
";B
40 L
=
SQR(A*A
+
B*B)
50
P. "A",
"B"
,
"L"
60 P. A ,B ,L
Now type
in the
program carefully
and
RUN.
Caarash!
The
WHAT?
40
L=S?QR(A*A
+
B*B)
tells us the
Computer does
not
recognize SQR.
That means
we'll
have to
call
up
the SQR
subroutine
from Appendix A to
make a
workable
program.
See the
list
at
the end of
this Chapter to
determine which
functions are
available as sub-
routines
in Appendix A.
Turn to
page 216 of
Appendix
A
and
find the
Square Root
Subroutine.
There
are three
important
things to look for
when checking
out
any
subroutine:
1.
What
is the input
variable?
2.
What
is
the
output variable?
156
Whenever you
come
across a
program with
aft
intrinsic function you
don't
have,
you'll
go
";t&roagh this
same
procedure.
First
type
in
the
§|
subroutine,
then make
a
few minor changes
in
ed.to#ei^t^;-
:
:
: