How to send variable in a text string?

Hi I am trying to send a variable in a text string

This is the code

mass_a=1;mass_b=2;mass_c=3;
set(gas,'nc7h16:mass_a:,o2:mass_b,n2:mass_c');

This is a part of cantera code I am using, I am trying to set mass fractions of certain species in a gas structure. As per cantera code I am suppose to set mass fractions through text string. but this I won't be able to run it in for loop. hence I wanted to give mass fractions before every run which I have as variables.

I don't know how to send variables in text string so the cantera code can read?

[dpb]

Is there a set method for whatever the variable gas represents? AFAIK, the MATLAB builtin function only operates on HG2 objects.

However, that's not the problem about writing text strings--just use sprintf or num2str or, if the syntax supports it, the newer string class.

mass_a=1;mass_b=2;mass_c=3;
cmd=sprintf('nc7h16:%d,o2:%d,n2:%d',mass_a,mass_b,mass_c);
set(gas,cmd);

for the specific case with unique variables and hardcoded species (and for the integer values you've chosen; if use more precise values, adjust the numeric format to suit the precision and format needed).

However, it would be more useful to be able to store the various information in arrays and generalize--

masses=[1;2;3];
species={'nc7h16';'o2';'n2'};
fmt=repmat('%s:%d',1,numel(masses));
cmd=[];
for i=1:numel(masses)-1
  cmd=[cmd,sprintf('%s:%d,',species{i},mass(i))];
end
cmd=[cmd,sprintf('%s:%d',species{numel(masses)},mass(numel(masses)))];
set(gas,cmd);

[Walter Roberson]

set() does work on more general objects, and special support for set/get methods is built into MATLAB's class support. But for class support, set() has to have 3 arguments: object, property name, and new value -- with the exception of the case where you are querying the permitted values, such as set(groot, 'Units') to get the list of values of Units that are permitted.