# what is inline(vectorize function), also why to use fliplr for this?

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Dhairya on 14 Nov 2022
Commented: Walter Roberson on 15 Nov 2022
clc
clear all
close all
syms x
f = input('Enter the function')
fL = input('Enter the interval on which the function is defined')
yr = input('Enter the axis of rotation')
iL = input('integration limits')
volume = pi*int((f-yr)^2,iL(1),iL(2));
disp(['Volume is: ',num2str(double(volume))])
fx = inline(vectorize(f));
xvals = linspace(fL(1),fL(2),201);
xvals = fliplr(xvals);
xivals = linspace(iL(1),iL(2),201);
xivalsr = fliplr(xivals);
xlim = [fL(1) fL(2)+0.5];
ylim = fx(xlim);
figure('Position',[100 200 560 420])
subplot(2,1,1)
hold on
plot(xvals,fx(xvals),'-b','LineWidth',2);
[X,Y,Z] = cylinder(fx(xivals)-yr,100);
figure('Position',[700 200 560 420])
Z = iL(1) + Z.*(iL(2)-iL(1));
surf(Z,Y+yr,X,'EdgeColor','none','FaceColor','flat','FaceAlpha',0.6);
hold on
plot([iL(1),iL(2)],[yr yr], 'r-', 'LineWidth', 2);
xlabel('X-axis');
ylabel('Y-axis');
zlabel('Z-axis');
view(22,11)

Chandler Hall on 14 Nov 2022
Edited: Chandler Hall on 14 Nov 2022
Vectorize just adds some '.' to a string so that it might be used as a vectorized function, i.e.,
>> vectorize('(x^3)/y')
ans =
'(x.^3)./y'
Why use fliplr? That's impossible to say because it actually has no effect at all. xvals is only used in the subsequent plot, which produces the same output if the vectors are in ascending order vs descending, and xivalsr is unused.
##### 2 CommentsShowHide 1 older comment
Walter Roberson on 15 Nov 2022
Changing the order using fliplr() could potentially lead to a difference as to exactly where the "seam" is in the plot of the cylinder.

Steven Lord on 14 Nov 2022
Do not use inline. Its use has been discouraged for probably around 15 years now.
To convert a piece of text data to something that you can call as a function use str2func.
To convert a symbolic expression to something that you can call as a function use matlabFunction.
##### 2 CommentsShowHide 1 older comment
Steven Lord on 15 Nov 2022
See the documentation for str2func and matlabFunction for examples of how to use each function.