Error using * Too many input arguments.

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saravanakumar D 2013-12-31

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评论： Walter Roberson 2013-12-31

Error in triangle (line 9) ratio=c.Perimeter^2/(4*pi*c.Area);

I am getting the above error,I have binary image of triange, so i want use perimeter area ratio to detect the shape, but unfortunately i get this error. I don't know why.

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Answer 1

Walter Roberson 2013-12-31

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Your "c" is a structure array, so c.Area is expanding to multiple arguments.

ratio = [c.Perimeter].^2 ./ (4 * pi * [c.Area]);

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saravanakumar D 2013-12-31

编辑：saravanakumar D 2013-12-31

It's working thank You.

Can you please tell me. why we use [] and .

Walter Roberson 2013-12-31

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When you have a structure array "c", then c.Area is the same as if you had written out

c(1).Area, c(2).Area, c(3).Area, ... c(end).Area

all as individual arguments to the function. When you use [c.Area] then this becomes

[c(1).Area, c(2).Area, c(3).Area, ... c(end).Area]

and so becomes the vector containing all of the various c(K).Area values.

When you are using regionprops, you get a separate structure array entry for each region that regionprops finds. If you get back (say) 3 areas, then the areas will not be stored as [c.Area(1), c.Area(2), c.Area(3)] and are instead stored as c(1).Area(1), c(2).Area(1), c(3).Area(1) -- three separate vectors, not a vector with three entries. Using [c.Area] puts all the entries together into a single vector.

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