Radio Shack TRS-80 Model 100 Basic Manual page 114

230
225
325
280
345
380
140,
155,
220,
285,
255,
315,
800 PSET (34,Y) : NEXT Y
700 FOR X
=
0 TO 28 STEP 4
710 PRINT@ 284+X,X; : NEXT X
720 FOR Y
=
1 TO 7
730 PRINT@ 280-Y*40, 100+Y*50
740 NEXT Y
745 PSET (38,50)
750 FOR X = 1 TO 24 : READ Y
780 LINE -(33+X*8, 54-(Y-138)/8.25)
770 NEXT X
800 DATA 180, 175,
810 DATA 155, 215,
820 DATA 215, 285,
830 DATA 225, 270,
840 DATA 275, 350,
850 DATA 300, 330,
2000 GOTO 2000
Execute the program and you should see the display
l
0':\ ..
A ..- • : ••••••••••
I'.
~
..,
II •
1'.
J :
a,;
"',
.
..
..
."
-.,
.
1 \/\:
.......... ...
-:
450
400
350
300
250
200
150
o
4
8
12 16 20 24 28
You will have to press
~
to terminate execution of this program.
Line 745 The PSET statement turns on the graphic cell for the first quarter sales
point.
Line 768 The LINE statement draws a line from the last cell referenced to the next
sales point. Recall that the first coordinate in the LINE statement is optional, and if
omitted, draws a line from the last referenced cell. In this case, the second coordinate
of the LINE statement becomes the first coordinate for the next line. LINE 745 is
required so that the graph starts with the first data point.
Experiment #8 Draw the Trend Line
Recall from Lesson 7 that the trend line for the sales data we have been plotting is
given by the equation
Y
=
148.225
+
8.4087
*
X
108