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

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.

[Walter Roberson]

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]

Thanks for replying.

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

Answer 1

[Stephen Cobeldick]

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

v = 1×9

1 2 1 2 1 2 1 2 1

[cheng en tsai]

thank you guys!

[Walter Roberson]

Three instructions

[Stephen Cobeldick]

@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.

Answer 2

[Matt J]

X=ones(1,n);
X(2:2:end)=2;

[Walter Roberson]

three instructions