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Pixel coordinates
The figure below shows the graphic coordinates for the typical (minimum)
screen of 131×64 pixels. Pixels coordinates are measured from the top left
corner of the screen {# 0h # 0h}, which corresponds to user-defined coordinates
Data set 1 Data set 2
xy x y
0.4 6.3 0.7 4.8
1.0 4.9 1.0 3.0
2.0 4.3 1.5 2.0
3.4 3.0 2.2 0.9
4.0 1.2 3.5 0.4
5.8 2.0 4.5 1.0
7. 2 3 . 8 5 . 0 2 .0
7. 8 5 . 3 6 . 0 2 .5
9.0 7.2 7.1 2.0
8.0 0.7
9.0 0.0
10.0 1.5
10.5 3.4
11.0 5.0
Note: The program FRAME, as originally programmed (see diskette or CD
ROM), does not maintain the proper scaling of the graph. If you want to
maintain proper scaling, replace FRAME with the following program:
« STOΣ MINΣ MAXΣ 2 COL DUP COL DROP – AXL ABS AXL 20 /
DUP NEG SWAP 2 COL + ROW DROP SWAP yR xR « 131 DUP
RB SWAP yR OBJ DROP – xR OBJ DROP - / * FLOOR RB
PDIM yR OBJ DROP YRNG xR OBJ DROP XRNG ERASE » »
This program keeps the width of the PICT variable at 131 pixels – the minimum
pixel size for the horizontal axis – and adjusts the number of pixels in the
vertical axes so that a 1:1 scale is maintained between the vertical and
horizontal axes.