my result and the book result are different. where is wrong?

i have r and theta boundary. i try to and y plane horizontal, Sx is vertical plane.x and y depend variable r and theta, so x=r.*cos(theta) and y=r.*sin(theta).but something is wrong. my result and the book result are different.my result is:

the codes:

[Sean de Wolski]

What's the difference between the two. The viewing angle is all that looks different to me.

[Bugra]

its not about viewing angle. when look at the cross the plane u see diffence.

[Star Strider]

@Bugra — Please re-post your original question here.

If this is a new problem, ask a new Question. Very few people pay attention to Questions with Accepted Answers, and they are unlikely to respond to them even then.

(The original Question involved the difference between a plot in the textbook and the plot the code in the textbook produced. The Answer was that the book plot used a different value for the radius than the text did, so the plots looked slightly different. The code and the plot figure .png were included.)

Answer 1

[Star Strider]

The book plot cuts off at 0.15 in x and y, your plot cuts off at 0.2. That’s the only difference I see.

Change ‘r’ to:

r = linspace(0.02, 0.15, 20); %20 values between 0.02 and 0.15

and add an axis call after the mesh call:

axis([0  0.2    0  0.2    zlim])

and you reproduce the book plot.

[Bugra]

yes thank u for ur solution. but the range is 0.02<=r<=0.2 .i cant change this.r must be between this range.

[Star Strider]

My pleasure.

Keep it as in your original code:

r = linspace(0.02, 0.2, 20); %20 values between 0.02 and 0.2

Apparently the book used an upper limit of 0.15 for ‘r’ in the plot, and the text specifies an upper limit of 0.2.

My intent is to reassure you that your code is correct, that the only difference is that the book used different limits for the figure than it did in the text, and then did not tell you about the change. My guess is that the author later decided to emphasise the asymptotic nature of the function as ‘r’ increased.

[Bugra]

thank you so much. i understand the difference now thanks to you. i think the book use wrong range in graph.i appreciated.

[Star Strider]

My pleasure!

The book definitely uses a different range for ‘r’ than the one it wants you to plot.