Plot {(x,y,z)| x²+y²<1, 0<z<x+2}

I'm not sure abot the code, because of the 2 constraints. I hope someone can help me.

Answer 1

[Constantino Carlos Reyes-Aldasoro]

It depends on what you want. One way to code this would be to define your space, i.e. the range of each of each variable, say x goes from -5 to 5 in steps of 0.1:

x=-5:-.1:5;

and the same for y and z. Then x^2 + y^2 < 1 becomes a condition, those points below 1 could be selected and those above discarded, then you do the same with the second condition and your answer could be a cloud of points where the two conditions intersect.

Answer 2

[Rik]

Same general idea as @Constantino Carlos Reyes-Aldasoro, but more in steps.

Use linspace or colons to create one or three vectors to define your coordinate grid.

Then you can use ndgrid or meshgrid to expand that/those vector(s) to a full grid.

Now use element-wise operations (.* and ./ and .^) to compute . The logical operators < and > will work element-wise by default.

Now you have logical arrays where the combination of x,y,z is either valid or invalid. You can use logical indexing to either remove them, or mark a value array with NaN.

Now you have x y and z vectors, which you can input to a function like plot3 to show the pointcloid.