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Icon Analyst 52 -- Supplementary Material
Last updated February 6, 1999
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A Weaving Language
Weaving Procedures |
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Pattern Forms Revisited
Conversion Procedure |
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Answers to Quiz on Structures
1. False. L[0] is an attempt to reference an element beyond the end of L , which fails.
2. True.
3. They both produce the same results, but the first leaves L unchanged, while the second removes all its elements, leaving it empty.
4. It adds a null-valued element to the right end of L .
5. They all leave L unchanged, although some differ in intermediate steps.
6. L := sort(set(L)) .
7. True.
8. False.
9. False.
10. False. If R has a field named center , they produce the same results, but if R doesnt have a field named center, R.center causes a run-time error, while R["center"] fails.
11. True.
12. True.
13. False.
14. False; the order is unpredictable but not random.
15. *sort(S) .
16.
procedure elim_str(S)
every x := !S do
if type(x) == "string" then delete(S, x)
return S
end
17. set(R) , set(S), set(T) , and list(S) cause run-time errors. table(S) creates a table whose default value is S .
18. True.
19. False in general.
20.
procedure keyset(T)
S := set()
every insert(S, keys(T))
return S
end
21. Values can be obtained from keys, as in T[key(T)] . The converse is not true.
22. True, although this is a property of the implementation and not specified in the language.
23. False. Although there is no language or implementation limit on the number of elements in a table, it must fit in memory, which is limited. |
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Graphics Corner -- Transparency
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Figure 1. The Affect of Transparency
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Figure 2. Unicorn Silhouette
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Figure 3. A Numerical Carpet
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Figure 4. Unicorn Adorned with a Carpet
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Figure 5. Other Unicorn Adornments
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Figure 6. The Images for Masks
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Figure 7. Shuttering the Unicorn
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Animation -- Mutable Colors
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Figure 1. Marquee Layout
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Figure 2. Successive Marquee Images
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Figure 3. Path Layout
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Figure 4. Snapshots of the Worm
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Figure 5. An Expanding Ring
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Figure 6. Revolving Rotors
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Figure 7. Revolving Color Wheel
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From the Library -- PostScript Graphics
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Figure 1. Screen Image
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Figure 2. Enlarged Screen Image
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Figure 4. Color Artifact in Reversible Drawing |
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As the article points out, we cant show the reolution independence of PostScript images in a bit-mapped medium like this Web page. Here are links to the PostScript files in case you want to print them yourself.
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Programs |
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Orbit animation (17k) |
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Awake animation (102k) |
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Graphics Corner -- Transparency |
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Figure 5. Pixel Rendering
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Figure 1. Black and White Queens |
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Icon home page |
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