MATLAB: BUG in subs()

Question

   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?

Answer 1

This is functionality available for backward compatibility. If the old does not occur, but the new does, it switches them.

doc subs