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1.1 root 1: .NH 1
2: A ``startup'' function in \*a?
3: .PP
4: \*a has a startup facility
5: which allows automatic execution
6: of an \*a expression when a
7: workspace is loaded.
8: If you define the variable
9: ``\*(qdlx'' to be some \*a expression
10: and then save the workspace,
11: when you next ``)load'' the
12: workspace,
13: \*a will automatically read
14: and execute ``\*(qdlx''.
15: For example,
16: if you have the function ``hello''
17: which looks like this:
18: .DS
19: hello
20: [1] \'hi there, my friend\'
21: [2] \'welcome to apl\'
22: .DE
23: and
24: you want \*a to perform
25: ``hello'' when you load
26: the workspace file ``hi'',
27: you can say:
28: .DS L
29: \*(qdlx { \'hello\'
30: )save hi
31: 14.59.31 10/26/78 saved hi
32: )off
33: .DE
34: Then, if you run \*a with:
35: .sp
36: $ apl hi
37: .sp
38: you will get:
39: .DS L
40: a p l \\\\ 1 1
41: 25 oct 1978
42:
43: 14.59.31 10/26/78 loaded hi
44:
45: hi there, my friend
46: welcome to apl
47:
48: \_
49: .DE
50: .NH 1
51: \*u \*a\\11 Limitations
52: .PP
53: \*u \*a does have
54: some limitations.
55: Tracing,
56: which is controlled by the
57: ``)trace'' and ``)untrace'' commands,
58: is not compatible
59: with the standard
60: \*a
61: trace facility.
62: .PP
63: Some operators have not
64: been implemented
65: (for example, laminate
66: is not supported).
67: Dyadic format is available in
68: a restricted form:
69: the left argument cannot be a
70: scalar or one-element vector
71: and negative precision
72: (``E format'')
73: is not permitted.
74: There is a function
75: /usr/lib/apl/fn/dft
76: which performs dyadic format
77: according to the standard definition.
78: Inner and outer product will not
79: work with character data.
80: .PP
81: Functions which are created with
82: ``\*(qdfx'' should not have the same
83: name as existing variables;
84: occasionally
85: \*a
86: gets confused and mistakenly
87: zaps a newly-fixed function.
88: Functions containing overstrikes
89: that were created by ``\*(qdfx''
90: cannot
91: be properly edited.
92: The only quad variable which has
93: been implemented is
94: ``\*(qdlx'',
95: and it is always a global variable.
96: .PP
97: The biggest limitation for PDP-11
98: \*u \*a is space.
99: Despite efforts to use as
100: much memory as \*u
101: and the computer itself permit,
102: only about 5000 numeric values
103: may be stored in an \*a
104: workspace.
105: In order to permit workspaces
106: containing more data,
107: there is a second version
108: of \*u \*a called ``apl2''.
109: \*(a2 is used exactly the
110: same way as \*a \(em
111: the only difference is that
112: it uses single precision
113: floating-point instead of
114: double-precision.
115: As a result,
116: some precision is lost,
117: but \*(a2 allows twice
118: as many workspace items
119: as \*a.
120: Although
121: \*(a2 and \*a workspaces
122: are in different formats,
123: \*a and \*(a2 will convert
124: each other's workspace files
125: they are loaded with ``)load''
126: or merged with ``)copy'',
127: so workspaces may be
128: used interchangably.
129: In all other respects,
130: the operation of \*(a2 is
131: identical to the operation of \*a.
132: (On the VAX 11/780,
133: the size of the workspace is essentially
134: limited only by the virtual memory system.
135: Hence,
136: \*(a2 provides no real advantage over \*a).
137: .PP
138: Finally,
139: an unfortunate restriction in using \*a
140: on both PDP-11's and VAX-11/780's is that
141: workspaces are not
142: directly interchangeable
143: between machines.
144: However,
145: there is a program to convert them.
146: To convert a PDP-11 workspace to the VAX,
147: run (on the VAX) the command:
148: .DS
149: $ aplcvt filename
150: .DE
151: The workspace will be converted to VAX
152: format and placed into the file
153: ``filename.vax''.
154: Similarly,
155: you can convert VAX format workspaces
156: to PDP-11 format by running
157: ``aplcvt'' on a PDP-11.
158: (There are other options available;
159: for a description of these see the
160: online manual by typing
161: .DS
162: $ help aplcvt <or> $ man aplcvt
163: .DE
164: .NH 1
165: Conclusion
166: .PP
167: Well,
168: that wraps up this manual.
169: Reference information about
170: \*a is found in the
171: online manual.
172: Type:
173: .DS
174: $ help apl <or> $ man apl
175: .DE
176: for the online document.
177: Good luck with \*a!
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