BUG in subs()?
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subs('N*g', 'N', 'tg/u')
subs('N*g', 'tg/u', 'N')
these two code lines give the same result:
(g*tg)/u
but the first line should give back:
(g*tg)/u
and the second result should be:
N*g
since there is no 'tg/u' which could be substitued...
techdoc says:
subs(S,old,new)
so i think it should only look for 'old' and change to 'new', not vice versa.
any idea how can i avoid that subs function changes 'new' to 'old' in the S expression?
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Accepted Answer
Sean de Wolski
on 23 Feb 2012
This is functionality available for backward compatibility. If the old does not occur, but the new does, it switches them.
doc subs
2 Comments
Walter Roberson
on 23 Feb 2012
This is *documented* functionality.
http://www.mathworks.com/help/toolbox/symbolic/subs.html
If subs(s,old,new) does not change s, subs(s,new,old) is tried. This provides backwards compatibility with previous versions and eliminates the need to remember the order of the arguments. subs(s,old,new,0) does not switch the arguments if s does not change.
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