MATLAB: Try to answer bonus question

MATLAB

Screenshot is attached. Comment what the code to the bonus question is. Also provide explanations.

Best Answer

By using primes built in function of MATLAB:

function y=prime_count(n)
y=numel(primes(n));
plot(primes(n))
end

From command line:

prime_count(10)
>>   4

Related Solutions

MATLAB: Is there a way to remove the nested for loops from this segment of code? I’m trying to make the code generic so it can take in n-number of moment arrays.

Hello Joseph, I believe this does what you want. It assumes you have a 3d array called momentarray, containing an arbitrary number of moment matrices. It should work for any number of moment matrix rows and columns. I called each moment matrix a layer in the 3d array. S is the result.

The code does not preallocate any arrays so it is inefficient that way but it is still fast enough for reasonably sized S.

n = size(momentarray,3);     % number of moment matrices
m = size(momentarray,1);     % number of rows in each moment matrix
S = momentarray(:,:,n);
layr = n-1;
while layr >= 1  
  rowS = size(S,1);
  temp = [];
  for j = 1:m                                   % loop over rows in a layer
    a = repmat(momentarray(j,:,layr),rowS,1);   % duplicate the row
    temp = [temp;a+S];                   % add to previous S and concatenate
  end
  S = temp;
  layr = layr-1;
end

MATLAB: How to find first ten prime numbers that are greater than 4

You could do it like this

x = primes(100); %pick primes smaller than, say 100
x = x(x>4); %pick the ones larger than 4
x(1:10) %pick the first ten of those

Best Answer

Related Solutions

MATLAB: Is there a way to remove the nested for loops from this segment of code? I’m trying to make the code generic so it can take in n-number of moment arrays.

MATLAB: How to find first ten prime numbers that are greater than 4

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