a way to use an empty char cell in inputdlg

Hi, and Merry Christmas at all

I need to use an inputdlg box with La Tex interpreter setted at

options.Interpreter = 'tex';

my prompts return from a for loop; so I used sprintf function:

for i=1:3  
    w = sprintf('\\alpha\ %d', i);
    e = sprintf('A %d', i);
    r = sprintf('\\theta\ %d', i);
    q = sprintf('D %d', i);
    z = sprintf('\\sigma\ %d (rot=0, prism=1)', i);
    Title = sprintf('LINK %d',i);
     prompt = {w,e,r,q,z};
     numlines=1;    
     answer=inputdlg(prompt,Title,numlines,defans, options);

but, since I don't care default answer, I thought to assign it an empty space like:

defans = {'','','','',''};

or

defans = cell(1,5);
defans{1} = char(defans{1});
defans{2} = char(defans{1});
defans{3} = char(defans{1});
defans{4} = char(defans{1});
defans{5} = char(defans{1});

but in both cases matlab returns the same warning message:

Warning: Escape sequence ' ' is not valid. See 'help sprintf' for valid escape
sequences.

I think because '' form is an Escape sequence for sprintf() function.

How can I use the LaTex interpreter and an empty space as default answer without Warning Message returning ?

[Kye Taylor]

Merry Christmas and all back at ya! haha

Answer 1

[Jan]

You need the string e.g. '\alpha 3'. You can create this by:

str = ['\alpha ', sprintf('%d', 3)]

or

str = sprintf('\\alpha %d', 3)

The backslash is the special character, which tells LaTeX that a command is following. The space is no valid format, such that '\ ' creates the shown error message.

The Backslash is a special character for sprintf also, e.g. '\n' means a line break. Therefore you have to escape it by another backslash, to get one backslash in the created string.

If this solves your problem, the question could be simplified:

 How can I create a string, which is displayed by the LaTeX interpreter as "\alpha 3", where \alpha means the Greek character and the number is taken from a variable?

Answer 2

[Walter Roberson]

backslash followed by space is not a valid sprintf() escape sequence.

Perhaps you need to use (e.g.) '\\\\alpha\\ %d'

[Marco]

ok but I think warning message refers to '' in default answer

[Marco]

means

''

in default answer

[Walter Roberson]

Use your debugger and step through that code; you will be able to isolate where the warnings are coming from.

[Jan]

@Marco: Why do you think, that the problem appears in defans = {'','','','',''}? sprintf('\ ') reproduces the warning, such that I'm convinced, that Walter is right.

Another way to create your default answer:

defans = cell(1,5);
defans(:) = {''};

[Marco]

@Jan: Because I thought since warning message types ' ' form in itself so..but I was wrong.

@Walter: You are right. With command:

dbstop if warning

it indicates me

w = sprintf('\\alpha %d\', i);

I tried to type only

w = sprintf('\alpha %d', i);

but it doesn't interpret Tex string

[Walter Roberson]

Try '\\alpha %d\\ '

[Marco]

I tried with '\\alpha %d\\' and it returns another warning message:

Warning: Unable to interpret TeX string "\alpha 1\"

and does not interpret. Instead I tried with:

'\\alpha %d\'

and it interprets but retuns the same warning message:

Warning: Escape sequence '' is not valid. See 'help sprintf' for valid escape
sequences.

[Jan]

What about omitting the trailing slash?

[Walter Roberson]

What string is it that you would like to reach LaTex ?

[Marco]

I would like to interpret alpha (as greek symbol) with the number of for-loop index i by %d.