why can't i draw diagram of function abs(sin3x/sin(x/2)) in matlab?

my code:

x=-pi:0.1:pi;
y=abs(sin(3*x)/sin(x/2));
plot(x,y);

Answer 1

[Star Strider]

Because you are not using element-wise division (with the ‘dot’ operator, as ‘./’).

This works:

x=-pi:0.1:pi;
y=abs(sin(3*x)./sin(x/2));
plot(x,y);

See the documentation on Array vs. Matrix Operations for all the details.

[Le Dung]

Thank you so much. Star Strider

[Star Strider]

As always, my pleasure.

[Le Dung]

If so, are you expert on Matlab?

[Star Strider]

I would not consider myself an ‘expert’, because MATLAB is extensive, and it is difficult to know everything about it. (For example, I have done little with GUIs.)

There are several areas where I consider myself acceptably competent.

[James Tursa]

Note that this might have had a problem if x had been defined in such a way that it had a 0 as one of the points between -pi and pi, since you would have had a 0/0 for y at that point and a NaN, resulting in a gap in the plot. But since the stepping selected happened to jump over the 0 point, there was no gap in this particular case.

[Le Dung]

Thank you so much

[Star Strider]

My (our) pleasure.