Help with problem?

What would the value of d be after the following code is executed?

>> vec = linspace(99,44,56);

>> vec = reshape(vec,8,7);

>> d = vec(length(size(vec(:,3))))

I know that the answer is 98, but I do not understand why. A thorough explanation of this would be appreciated. Thank you.

Answer 1

[TA]

After the second step, you get:

vec =

99 91 83 75 67 59 51

98 90 82 74 66 58 50

97 89 81 73 65 57 49

96 88 80 72 64 56 48

95 87 79 71 63 55 47

94 86 78 70 62 54 46

93 85 77 69 61 53 45

92 84 76 68 60 52 44

Third step: (length(size(vec(:,3)))) equals to 2 if you keep dissecting it. Basically, all columns i.e. vec(:,3) have a size of 8 x 1. And length of that "size" is 2.

And thus, you arrive at vec(2). Which is 98 as I indicated above.

[Anne Nguyen]

So just to clarify, vec(:,3) means to include all elements in the third column? And then from there, how is the length of that size = 2? I'm sorry, I'm just still a bit confused. Thank you very much.

[TA]

Yes. Anywhere you see a : that implies all elements are considered.

Length gives you the total number of elements in an array. The array size contains two elements i.e. 8 and 1.