COMPLEX.QQ overstrikes 
Author Message
 COMPLEX.QQ overstrikes

It falls to me to clear up some confusion that I have started.
        On closer examination, this file is not so unintelligible as I thought.
The ASCII characters of PC keys are directly mapped onto the IBM APL 360 key-
board. The backspaces and overstrikes in this file are needed to represent the
composite glyphs. If you print this file out and scrutinize it closely, you can
distinguish the following:

F over anything: This is underscore, underbar.
M over O : Reversal.
? over O : Transpose.
_ over / : Reduction-bar, /[1]

J over N : Format
P over O : Natural logarithm
J over C : This is "lamp", comment.

         An ambiguous symbol is "!", which on the APL 360 KB is the two dots in
the upper left corner. Here it is frequently used to set off text inside a com-
ment space. The reason for its presence on lines 7,8 of the function definition
"catan" is not clear. The printer compressed into one line what were two on the
screen in this case too.
         When you view this file on the computer, use a utility that wraps long
lines and displays all ASCII values. Vernon Buerg's LIST with the junk & star
filters turned off and wrap on is adequate. The file may appear differently un-
der different viewers, which rarely display overstruck characters. They may
display the printer control characters that make the printer overstrike, as the
ASCII diamond, etc.
         I'm glad now that the printer did backspace and overstrike, because I
know how to interpret them, although you can't do it this way on a PC.
         Lowercase letters in COMPLEX.QQ will be uppercase in APL. Uppercase
letters will be APL functions. Capital F is frequently used to underscore var-
iable names. This is rarely possible now-a-days and will have to be left out in
a consistent manner. Since you can't backspace on most micro APL's, you will
have to know which shifted or ALT keys give you those glyphs.
         The back-quote character ("`") appears frequently. On APL2, this is a
diamond. It is probably a statement separator, and has nothing to do with CTRL-
D, the ASCII 4 diamond, which is used in COMPLEX.QQ as a printer control device
         I haven't yet acted on the conclusions just presented and hope they
will not prove erroneous. If I be right, you and I will be able to expand our
repertoire to include complex arithematic, rare in languages besides fortran.



Sun, 31 Dec 1995 02:42:29 GMT  
 
 [ 1 post ] 

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