How to use anonymous function in linkage ?

I am trying to use my own function in linkage. https://www.mathworks.com/help/stats/linkage.html

I completely have no idea and this tutorial https://www.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html does not help at all because the anonymous function in linkage has no inputs.

This is my code currently based on

test = linkage(array,'single','@custom');

This is how my custom distance is defined

function distance = custom(data_a, data_b)
   distance = abs(data_a(1) - data_b(1)) + abs(data_a(2) - data_b(2))
end

can someone give me a good example of how I can call a @custom without any arguments ?

Answer 1

[Walter Roberson]

test = linkage(array,'single', @custom);

[RuiQi]

I am getting an error

Error using linkage (line 128)
Third input must be a string or a cell array.

My array is 100 x 5 double. My custom distance function is in a custom.m file in the same directory.

Z = linkage(array, 'single', @custom);
function distance = custom(data_a, data_b)
   w1 = abs(data_a(1) - data_b(1)) + abs(data_a(2) - data_b(2)) + abs(data_a(3) - data_b(3)) + abs(data_a(5) - data_b(5));
   distance = w1 * w1 / (1/data_a(4) + 1/data_b(4));
end

[RuiQi]

I think

Z = linkage(array, 'single', '@custom');

with the apostrophe worked.

[RuiQi]

If i have the function in the same .m file then

Z = linkage(array, 'single', @custom);

gives me the error

Error using linkage (line 128)
Third input must be a string or a cell array.

and

Z = linkage(array, 'single', '@custom');

says

Error using pdist (line 349)
The distance function 'custom' was not found.

Error in linkage (line 247)
           Z = linkagemex(Y,method,pdistArg, memEff);

[Walter Roberson]

Which MATLAB release are you using? The ability to use custom functions is not documented up to R2010b, but is documented starting with R2011a.