what is the error with that code?

clc
clear all
r=0.05;
l=0.01;
st=0.0001;
v=220;
Kf=18;
j=3;
Tl=60;
i=0;
w=0;
I=[];
W=[];
t=[];
for dt=0:0.0001:1
    I=[I i];
    t=[t dt];
    W=[W w];
    i=i+(((v-r*i)-(Kf*w)/l)*st);
     w=w+((((Kf*i)-Tl)/j)*st);
end
plot(t,W,'linewidth',4)
xlabel('time (sec)','fontsize','18','fontweight','b');
ylabel('SPEED (rpm)','fontsize','22','fontweight','b');
title('Dynamic model of separately excited dc motor under constant excitation');
axis([0 0.1 0.5])
gri;d
plot(t,I,'linewidth',4)
xlabel('time (sec)','fontsize','18','fontweight','b');
ylabel('current (A)','fontsize','22','fontweight','b');
title('current response of rl circuit');
axis([0 0.1 0.5])

Answer 1

[Setsuna Yuuki.]

clc
clear all
r=0.05;
l=0.01;
st=0.0001;
v=220;
Kf=18;
j=3;
Tl=60;
i=0;
w=0;
I=[];
W=[];
t=[];
for dt=0:0.0001:1
    I=[I i];
    t=[t dt];
    W=[W w];
    i=i+(((v-r*i)-(Kf*w)/l)*st);
     w=w+((((Kf*i)-Tl)/j)*st);
end
plot(t,W,'linewidth',4); hold on;
xlabel('time (sec)','fontsize',18,'fontweight','b'); %%Number without ('')
ylabel('SPEED (rpm)','fontsize',22,'fontweight','b');%%Number without ('')
title('Dynamic model of separately excited dc motor under constant excitation');
axis([0 0.5 0 0.5]) %% One limit more
grid on; %%(gri;d)
plot(t,I,'linewidth',4)
xlabel('time (sec)','fontsize',18,'fontweight','b'); %%Number without ('')
ylabel('current (A)','fontsize',22,'fontweight','b'); %%Number without ('')
title('current response of rl circuit');
axis([0 0.5 0 0.5]) %% One limit more

Answer 2

[Dennis]

You need to pass the FontSize as number and not as string:

xlabel('time (sec)','fontsize',18,'fontweight','b'); 
                                ^

You need to do this in the other 3 lines aswell.

Also use grid; instead of gri;d