Create an array with randomly selected elements

[lavezlas28]

I'm not familiar with MATLAB, and this year in our Introduction to DSP class, teacher gave us a homework but nearly none of us knows MATLAB much...

His question is;

Define a 1001-by-8 matrix, named “A”, whose elements selected randomly.
 Define an 8-by-1001 matrix, named “B”, whose elements selected randomly.
 Define a variable “C” as the multiplication of matrices “A” and “B”.
 Define a variable “D” as the mean value of the first column of “C”.
 Write the necessary code in script format.

 

[BradtheRad]

I do not know Matlab. If it is anything like BASIC, then you create arrays. One-dimensional, two-dimensional, etc.

Example, variable A is a two-dimensional array. Its format is A(x,y). Maximum size is either A(1000,7) or A(7,1000).

To fill it with random numbers, a common trick is to grab from some memory location which contains a rapidly-changing value. Example, a time counter. The counter must change very rapidly, or else values will not be random.

Perhaps Matlab contains a random number function.

 

[ads-ee]

Use google and look up matlab commands...e.g.
https://www.cs.cmu.edu/~tom/10601_fall2012/recitations/matlab_quickref.pdf
https://www.cogsci.uci.edu/~joachim/ss2012/MatlabCheatSheet.pdf

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As a hint
A=rand(4,3)
makes a random value matrix of 4x3 of course the random values are 0 < x < 1.

 

[weetabixharry]

The teacher does not specify what kind of random numbers he wants in A and B. I will assume he wants random numbers drawn from the standard normal distribution. Therefore:

 Define a 1001-by-8 matrix, named “A”, whose elements selected randomly.
A = randn(1001,8);

 Define an 8-by-1001 matrix, named “B”, whose elements selected randomly.
B = randn(8,1001);

 Define a variable “C” as the multiplication of matrices “A” and “B”.
C = A*B;

 Define a variable “D” as the mean value of the first column of “C”.
D = mean(C,1));

 Write the necessary code in script format.
This doesn't mean anything. Tell your teacher he's a lemon.