Unable to add xlabel to subplots with secondary axis

I was trying to add xlabel to subplots with secondary axis but i kept getting errors.

figure
p = subplot(1,2,1);
plot (tmin,capex,'r-o');
xlabel(p,'\Delta T_{min}')
ylabel('Total Capital Cost ($)')
yyaxis right
plot(tmin,opex,'g-*');
legend ('Total Capital Cost','Utility Cost/s')
ylabel('Utility Cost ($/s)')

ax2 = subplot(1,2,2)
....

The error message is as follows.

Function 'subsindex' is not defined for values of class 'matlab.graphics.axis.Axes'.

Error in Untitled (line 44)
xlabel(p,'\Delta T_{min}')

But without the xlabel, the graph appears perfectly with the ylabels and legend

Answer 1

[Ahmet Cecen]

The only reason I can think of for this to happen is if you used the name "xlabel" somewhere else in the code. I can replicate the error like this:

xlabel = 6
p = subplot(1,2,1);
xlabel(p,'aa')

Make sure xlabel is not used as a variable name in your code.