## Code for Figure 5.19

### main.m

```%% Copyright (C) 2001, James B. Rawlings and John G. Ekerdt
%%
%% This program is free software; you can redistribute it and/or
%% modify it under the terms of the GNU General Public License as
%% published by the Free Software Foundation; either version 2, or (at
%% your option) any later version.
%%
%% This program is distributed in the hope that it will be useful, but
%% WITHOUT ANY WARRANTY; without even the implied warranty of
%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
%% General Public License for more details.
%%
%% You should have received a copy of the GNU General Public License
%% along with this program; see the file COPYING.  If not, write to
%% the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
%% MA 02111-1307, USA.

% assoc_isotherm.m ;   fit to nonlinear form of isotherm
% jbr, 2/23/98
%

global CO P CO_s
%Pdata = [100,1.28;150,1.63;200,1.77;250,1.94;300,2.06;400,2.21];

ndata = size(Pdata,1);
ngrid = 20;
P = Pdata(:,1);
b = 1e6/(760*82.06*373);
CO =b*P;
CO_s = Pdata(:,2);
data = [CO CO_s];

%
% Find the best K_CO and c_m values for the isotherm
%

optimset ('TolFun', 1e-12);
guess = [10; 1];
[x, obj, info] = fminunc (@f, guess);
info;
K_CO = x(1);
c_m = x(2);

CO_grid = linspace(CO(1), CO(ndata), ngrid)';

CO_s_opt =  (K_CO*c_m*CO_grid)./(1 + K_CO*CO_grid);

output = [CO_grid CO_s_opt];

plot (output(:,1),output(:,2),data(:,1),data(:,2),'o');
axis ([3.8,18,1,2.4]);
title ('Figure 5.19')
```

### f.m

```function sqerror = f(x)
global CO CO_s
K_CO = x(1);
c_m = x(2);
CO_sc =  (c_m*K_CO*CO)./(1 + K_CO*CO);
diff = CO_s - CO_sc;
sqerror = diff'*diff;
```

## Data files

### assoc_isotherm.rdat

```100 1.28
150 1.63
200 1.77
250 1.94
300 2.06
400 2.21

```