Very basic: Could someone please explain what the 2 stands for in "size(v,2)" ?

V=[5 6 7 8]

size(v,2)

Could someone please explain what the 2 stands for in "size(v,2)" ?

Answer 1

[Bjorn Gustavsson]

You'll need to learn to read the help and doc for matlab-functions and commands. Also: welcome to matlab.

For this time only: size(v,2) will give you the size of v in the second dimension.

HTH

[CP]

Thanks a lot. I used actually the help function and I know that the second dimension is meant.

I guess I still dont really know what a dimension actually is? For example, I dont understand why in the following 2 cases, only the first works (meaning I get v displayed). If I run "2)" the answer I get is "1", and I dont get why.

I have tried the help and doc function, but it still doesnt seem to add up. I am really trying here.

1)

v = [1 2 3 4];

for i=1:size(v,2)

disp(v(i))

end

2)

v = [1 2 3 4];

for i=1:size(v)

disp(v(i))

end

[Steven Lord]

When you call size with one input argument and one output argument (which you are when you use it as the input to another function or operator), the output argument is a vector whose element k is the size of that input in dimension k.

matrix3x4x5 = rand(3, 4, 5);
size(matrix3x4x5) % [3 4 5]

When you call the colon operator : with a vector for one of the endpoints (or the increment) MATLAB ignores all elements other than the first.

aVector = [4 6 9 22 Inf];
anotherVector = 1:aVector % equivalent to 1:aVector(1) or 1:4

When you call size with two input arguments, the output is the size of the first input in the dimension specified by the second input. If that second input is 1, the output is the number of rows in the first input (basically how many rows get "collapsed" into one in the picture in the description of the dim input argument on this documentation page.) A second input of 2 gives the number of columns in the first input.

size(matrix3x4x5, 2) % 4 since size(matrix3x4x5) returns [3 4 5]

[CP]

Thank you