Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

# Half Point Algorithm for Dot Matrix Display

IP.com Disclosure Number: IPCOM000052211D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 35K

IBM

## Related People

Chen, SD: AUTHOR [+2]

## Abstract

A curve of a known function Y=f(X) is approximated on a dot matrix display (such as a gas panel) by a succession of monotonic steps of illuminated dots. Thus, data for controlling the display is formed in horizontal or vertical slices. The nearest dot to the true function is found by calculating the value of X from half integral values of Y. Fig. 1 illustrates a half-point algorithm flow chart, while Fig. 2 shows a graph of a function Y=f(X) to be approximated on a dot matrix display. Points at the intersection of row and column lines can be illuminated, as represented by the small circles in the drawing. The half integral values of the Y coordinate act as shown by the dashed lines.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 67% of the total text.

Page 1 of 2

Half Point Algorithm for Dot Matrix Display

A curve of a known function Y=f(X) is approximated on a dot matrix display (such as a gas panel) by a succession of monotonic steps of illuminated dots. Thus, data for controlling the display is formed in horizontal or vertical slices. The nearest dot to the true function is found by calculating the value of X from half integral values of Y. Fig. 1 illustrates a half-point algorithm flow chart, while Fig. 2 shows a graph of a function Y=f(X) to be approximated on a dot matrix display. Points at the intersection of row and column lines can be illuminated, as represented by the small circles in the drawing. The half integral values of the Y coordinate act as shown by the dashed lines.

First, a starting point X1, Y1 of the function is set equal to a starting point X1, Y1 on the display, and the end point of the curve is calculated. Next, the inverse function X2=f/-1/ (Y1+0.5) is calculated. As the drawing shows, the value X2 lies along the X axis at the intersection of the curve Y=f(X) and the coordinate line Y=Y1+0.5. As can be seen from the drawing, the portion of the curve between X1 and X2 is closely approximated by three illuminated dots along the line Y1. Immediately to the right of X2, the curve is best approximated by one or more points along the line Y2.

As the procedure just described is continued, the next value of X is compared with the previous value of X. If the curve rises at more than an angle of 45 degrees...