noxz-sites

A collection of a builder and various scripts creating the noxz.tech sites
git clone https://noxz.tech/git/noxz-sites.git
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noxz.tech/articles/crossing_out_expressions_in_eqn/index.www
1You can read about defining a macro for canceling an expression in the
2.I man
3page of
4.I eqn .
5This macro draws a line over the expression, as an indication that it’s
6canceled. When using paper and pen, I usually use a cross instead, so this is
7how you do the same in
8.I eqn .
9
10.CDS
11.COS
12\&.\\" define cancel_cross macro for expressions
13\&.defcolor cancelcolor rgb 0.0f 0.0f 0.0f
14\&.EQ }
15define cancel_cross 'special Cax'
16\&.EN
17\&.de Cax
18\&.  ds 0s \\
19\\Z'\\\\*(0s'\\
20\\Z'\\D't 0.75p''\\
21\\m[cancelcolor]\\
22\\v'\\\\n(0du'\\
23\\D'l \\\\n(0wu -\\\\n(0hu-\\\\n(0du'\\
24\\h'-\\\\n(0wu'\\
25\\D'l \\\\n(0wu \\\\n(0hu+\\\\n(0du'\\
26\\v'-\\\\n(0hu-\\\\n(0du'\\
27\\Z'\\D't 0.5p''\\
28\\m[default]\\
29\\v'\\\\n(0hu'
30\&..
31.COE
32.CDE
33
34Then use it, for example, like this:
35.ICD "{ 4 times 1 } over { 4 times 5 } = { cancel_cross 4 times 1 } over { cancel_cross 4 times 5 }" .
36
37You can, of course, name your macro
38.ICD cancel
39instead of 
40.ICD cancel_cross .
41The
42.ICD cancelcolor
43is also optional, and in the case above, redundant.