how to find index a subset elements from a set of points

Dear,

I have this set of points.

Z =[23.46, 22.125, 22.308, 22.119, 21.098, 23.018, 20.356, 27.731, 26.388, 26.278;  21.138, 22.651, 21.256, 28.346, 24.288, 29.082, 24.21, 29.952, 23.362, 23.474]';

I found the index for Z then I select some subsets and I need to know their index from the set Z. is their any cheap idea please. I don't want to use some expensive code.

x1=[23.46, 22.125, 22.308;
    21.138, 22.651, 21.256]';
x2=[21.098, 23.018, 20.356;
    24.288, 29.082, 24.21]';
x3=[27.731, 26.388, 26.278;
    29.952, 23.362, 23.474]';

many thanks

Answer 1

[Walter Roberson]

Use the second output of ismembertol or ismember

[Walter Roberson]

[tf, idx] = ismembertol(x1, z)

The location where tf is false were not found in z. The location where tf is true, the corresponding idx entry tells you where in Z it is

[Raymond MacNeil]

That is a great function! Thanks!