How can I create a vector like this : X = [1, 2, 1, 2 ......

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cheng en tsai 2021-3-2

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https://ww2.mathworks.cn/matlabcentral/answers/760121-how-can-i-create-a-vector-like-this-x-1-2-1-2

编辑： Stephen23 2021-3-2

采纳的回答： Stephen23

Hi,

How can I create a vector X = [ 1, 2, 1, 2 ....... ] with n value.(which n value can be odd or even).

Is there possible to use only two instructions?

thanks.

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Walter Roberson 2021-3-2

Is there possible to use only two instructions?

No. You need a minimum of 3 instructions even for the case where n is even. You can construct 1:2 or [1 2] but either way that takes one instruction. You need to divide n by 2, which takes one instruction. Replicating the vector takes a minimum of 1 instruction.

You can do the whole thing in four instructions if it is acceptable to have two assignment statements. I think it might take 6 instructions if you are only permitted to use a single assignment statement.

cheng en tsai 2021-3-2

Thanks for replying.

If I want it to use only one assignment statement, how can I deal with it especially when n is odd?

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Answer 1

Stephen23 2021-3-2

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https://ww2.mathworks.cn/matlabcentral/answers/760121-how-can-i-create-a-vector-like-this-x-1-2-1-2#answer_636941

在 MATLAB Online 中打开

n = 9;
v = 2-mod(1:n,2)
v = 1×9
     1     2     1     2     1     2     1     2     1

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Walter Roberson 2021-3-2

Three instructions

Stephen23 2021-3-2

编辑：Stephen23 2021-3-2

@Walter Roberson: yes, I also noticed that.

I suspect that "instructions" is as equally well-defined by the same professors/tutors/teachers who also specify no "inbuilt" functions. In some sense, even the hard-coded numbers are "instructions" to the MATLAB parser.

Perhaps the person who set this assignment can clarify this for us.

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