Plot, Expression or statement is incorrect--possibly unbalanced (, {, or [.

    %plot graphs
    hold on
    plot(wt,m,'b')
    xlabel('Time (s)')
    ylabel('Torque (Nm)')

The error is showing for the ylabel line

[Ken Atwell]

Looks okay to me, can you attached a screenshot?

[Chad Greene]

I suspect the problem is actually somewhere else in your code. An unterminated parentheses or bracket can confuse Matlab regarding where exactly the problem is.

[Image Analyst]

I bet you retyped your code into your question. Copy and paste the code instead. Take several lines before also. Most likely the problem occurs several lines above.