how can i contour level control use with 'plot'

I want Contour level control in my code

I know how to control the basic contour level,

I don't know contour level control with 'plot' and 'fit' code

how to 'Contour' level control? please teach me (Make the contour spacing more detailed.)

and i want specific number of contour values can be printed out(contour <0 or contour>0)

Please explain it with a picture

x=[1200	1200	1200	1200	1100	1100	1100	1100	1000	1000	1000	1000	900	900	900	900]';
y=[-2	-1	0	1	-2	-1	0	1	-2	-1	0	1	-2	-1	0	1]';
z=[0.577605826	0.488558387	0.45273093	0.478115298	0.547461689	0.460354119	0.420345944	0.43529964	0.497821842	0.370804822	0.305371971	0.318197107	0.416543949	0.372316357	0.339559983	0.319807786]';
f = fit( [x, y], z, 'cubicinterp' )

     Piecewise cubic interpolant:
       f(x,y) = piecewise cubic surface computed from p
     Coefficients:
       p = coefficient structure

ph = plot(f, 'Style', 'Contour');
set(ph, 'Fill', 'off', 'LineColor', 'auto');
grid off;
C = get(ph, 'ContourMatrix');
clabel(C, ph);

Answer 1

[DGM]

You can set the LevelList property

x=[1200	1200	1200	1200	1100	1100	1100	1100	1000	1000	1000	1000	900	900	900	900]';
y=[-2	-1	0	1	-2	-1	0	1	-2	-1	0	1	-2	-1	0	1]';
z=[0.577605826	0.488558387	0.45273093	0.478115298	0.547461689	0.460354119	0.420345944	0.43529964	0.497821842	0.370804822	0.305371971	0.318197107	0.416543949	0.372316357	0.339559983	0.319807786]';
f = fit( [x, y], z, 'cubicinterp' );

ph = plot(f, 'Style', 'Contour');
set(ph, 'Fill', 'off', 'LineColor', 'auto');
ph.LevelList = linspace(0.2,0.6,20); % just pick some levels
grid off;
C = get(ph, 'ContourMatrix');
clabel(C, ph);

[준희 박]

Thanks DGM