MATLAB: How the remove single apostrophe from a string

convert to functionfunctioninputsingle quotestr2funcstringuser input

yfunc=input('Enter any curve equation>') %If input yfunc= 'x^2', how to remove the apostrophe so that I can use the equation…

Best Answer

"how to remove the apostrophe so that I can use the equation..."
You can't, because a char array does not really have single quotes at the ends (unless you put them there), in just the same way the a numeric array does not contain any square brackets at the ends: the single quotes / square brackets are just the syntax that specifies how char arrays / numeric arrays are defined, but are not actually contained within the array itself. Let me demonstrate:
>> char(39) % single quote ASCII code
ans = '
>> double('hello') % get the ASCII codes for |hello|
ans =
   104   101   108   108   111
Can you see the code value 39 anywhere in that list?
In any case, if you have a char array then there is nothing that can be removed that will magically turn that char array into a function. A char array is just a collection of characters, which have no meaning other than any semantic meaning from how they were defined. If those characters happen to form a function in some variable then you will need to convert it into a function using str2func, I have shown you how below:
>> str = input('Enter function of x: ','s');
Enter function of x: x.^2+x
>> fun = str2func(sprintf('@(x)%s',str));
>> fun(0:10)
ans =
     0     2     6    12    20    30    42    56    72    90   110
Note that this will work as long as the function is entered using MATLAB syntax. If you want to define your own syntax then you will have to write a language parser using MATLAB, which is not a trivial task.
You really need to revise basic MATLAB types, such as what are char arrays and functions, because otherwise using MATLAB will not make sense:
https://www.mathworks.com/help/matlab/matlab_prog/fundamental-matlab-classes.html
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