How to replace string but not function

Dear Community,

In a string like: 'sinh(x).*f.*n'

I want to replace the n with X_Model(1). Using strrep however I end up with

siX_Model(1)h.*f.*X_Model(1)

which means that the n in sinh was also found to be an n and replaced. How can I make it exclusiv, so only if it matches exactly the replacement does take place? In a Matlab Script using 'Find and Replace' I can make this happen when I click 'Match Case' and 'Whole Word', so I want to have this functionality in a function.

Thanks and best Regards Ravi

Answer 1

[Sean de Wolski]

This can be done elegantly and safely with Symbolic Math Toolbox

syms x f n model(ix)
expr = sinh(x).*f.*n
subs(expr,n,model(1))

[Ravi Goyal]

Thanks Sean,

Would you know of any way not using the Symbolic Math Toolbox? Best Regards Ravi

[Sean de Wolski]

Not a safe way that is completely fool proof.

Answer 2

[Jan]

Str  = 'sinh(x).*f.*n'
Str2 = regexprep(Str, '\bn\b'

I cannot test this currently.

[EDITED]

Str2 = regexprep(Str, '(?:^|\W)n(?:$|\W)', 'X_Model(1)')

[Ravi Goyal]

Hey Jan, I also thought about somehow using regexprep but cannot get it to work. Your solution sadly also does not work.

[Jan]

@Ravi: See [EDITED] Please test this exhaustively, because I'm not a regexp hero.

[Ravi Goyal]

Thanks Jan,

It does the job for the n but then fails for the normal replacement of x in sinh(x) by getting rid of the brackets...I guess i gotta go somehow with the symbolic toolbox or just leave it a known bug.