... Language¹

This problem set was developed by Hal Abelson, based upon work by Peter Henderson (``Functional Geometry,'' in Proc. ACM Conference on Lisp and Functional Programming, 1982). The image display code was designed and implemented by Daniel Coore.

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... assignment.²

Section 2.2.4 does not depend very strongly on section 2.2.3, so you can start working on this problem set without reading 2.2.3. Be sure, however, to read all of section 2.2 before lecture on September 24.

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... painter.³

The images are kept in the directory specified by the variable 6001-image-directory. These images are accessible in a shared directory in the lab, and they are loaded as part of the PS3 problem set code if you are using your own computer. Use the Edwin command M-x list-directory to see the entire contents of the image directory. Each image is $128\times 128$, stored in ``pgm'' format.

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... interesting.⁴

Painting a primitive image like rogers won't look any different at high resolution, because the original picture is only $128\times 128$. But as you start stretching and shrinking the image, you will see differences at higher resolution.

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... painters.⁵

If setup (or painting) does not work, there are several things that could be wrong. Your data abstraction definitions might be incorrect. Or the system might not be able to locate the image files or the compiled code files need for this problem set. Whatever the problem is fix it now, getting help if necessary, before going on.

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... points⁶

We will use ``points'' and ``vectors'' interchangeably for this problem. Again, you can think of a vector as defining a point.

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