CODEWITHSUNDEEP
matlabmatrix
Matteo
Matteo

Reputation: 33

Initialize a matrix with condition

I'm new in MATLAB and I need help. I have to complete a code that initializes a matrix, but I don't know where to start.

The matrix must be in this form: enter image description here

Where Yi = i/m for i = 1, ..., m, with m=6.

The code to complete is:

m = 6;
A = [1:m;
     1:m;
     ...];

A = A/m;

Upvotes: 1

Views: 80

Answers (2)

rinkert
rinkert

Reputation: 6863

You can use implicit expansion. 

m = 6;
A = ((1:m).'/m).^(0:m);

Explanation. First make a column vector with the values y1 till ym. 

c = (1:m).'/6;

Then make a matrix, in which the first column will be c to the power of 0, the second c to the power of 1, etc.

You can do this easily with implicit expansion, take your column vector and raise to the power (element wise) of the row vector containing 0:m. 

A = c.^(0:m);

Upvotes: 4

ThomasIsCoding
ThomasIsCoding

Reputation: 101558

Here are two approaches:

  • use vander + fliplr
A = fliplr(vander((1:m)/m));
  • use arrayfun + vertcat
C = arrayfun(@(x) x.^(0:m),(1:m)/m, 'UniformOutput', false);
A = vertcat(C{:});

Result

>> A
A =

   1.000000000   0.166666667   0.027777778   0.004629630   0.000771605   0.000128601   0.000021433
   1.000000000   0.333333333   0.111111111   0.037037037   0.012345679   0.004115226   0.001371742
   1.000000000   0.500000000   0.250000000   0.125000000   0.062500000   0.031250000   0.015625000
   1.000000000   0.666666667   0.444444444   0.296296296   0.197530864   0.131687243   0.087791495
   1.000000000   0.833333333   0.694444444   0.578703704   0.482253086   0.401877572   0.334897977
   1.000000000   1.000000000   1.000000000   1.000000000   1.000000000   1.000000000   1.000000000

Upvotes: 2

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