MATLAB Matrice Function Question help please?
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I am trying to write a matlab program which creates an n by n matrix with the following:
a = [0 1 2 3 4; 1 0 1 2 3; 2 1 0 1 2; 3 2 1 0 1; 4 3 2 1 0]
How would I go about doing this?
42 minutes ago
- 4 days left to answer.
Additional Details Also looking like this:
a =
0 1 2 3 4
1 0 1 2 3
2 1 0 1 2
3 2 1 0 1
4 3 2 1 0
Some detailed instruction/help would really help me in clarifying how to program matrices in general.
采纳的回答
Kye Taylor
2012-4-5
It's a toeplitz matrix... so use the command
toeplitz(0:4)
to recreate your example. I'm sure you can extrapolate to the general n-by-n case.
More generally, if you want to create a matrix, use an array creation function like toeplitz, ones, rand, (type
doc elmat
and check out 1.) the list of Specialized matrices at the bottom of the help file and 2.) the list of elementary matrices at the top of the file.)
Beyond array creation functions, you can concatenate values both horizontally and vertically to create a vector/matrix/high d array. One way to concatenate is with square braces. For example, to concatenate 1 and 2 horizontally, use the command
v = [1,2]
That is, commas in square brackets can be interpreted as horizontal concatenation. To concatenate vertically, use the command
v = [1;2]
That is, semicolons in square brackets can be interpreted as vertical concatenation.
To build a matrix, construct it row-by-row sequentially from the first row to the last row. For example, the command
a = [0,1,2,3,4;1,0,1,2,3]
constructs the first row (0,1,2,3), then concatenates vertically (;) the second row (1,0,1,2,3);
That may not be the clarification you were looking for, so let me know if I can clarify.
2 个评论
Reelz
2012-4-6
Kye Taylor
2012-4-7
I like Image Analysts approach below... you could simplify with just
function m = makeToeplitz(n)
m = toeplitz(0:n);
更多回答（2 个）
Image Analyst
2012-4-6
For example, write this in the editor window (Use File->New if you have to, or click the blank page icon to get a new editor window):
function m = test1(n)
if nargin >= 1
m = toeplitz(0:n);
else
m = toeplitz(0:4); % Default
warningMessage = sprintf('Using default n of 4');
uiwait(warndlg(warningMessage));
end
and save it as test1.m. Then you can run it without any args and it will use a default of 4, or you can say
>> test1(5)
and it will use an n of 5.
3 个评论
Reelz
2012-4-6
Walter Roberson
2012-4-7
You have accidentally saved a file under the name toeplitz.m . Remove your file with that name.
Kye Taylor
2012-4-7
Impressive debugging :)
Andrei Bobrov
2012-4-7
out = abs(bsxfun(@minus,0:4,(0:4)'))
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