Error creating matrix using a integer and vector in Matlab

I'm having trouble understanding why I can''t declare a matrix by using the following declaration A = [1 x x.^2 x.^3]; where x is from a column vector of 1x50 double

Answer 1

[madhan ravi]

A = x(:) .^ (0:3)

[Syed Masoom]

Sorry that was my mistake on posting the question. I updated it. the error im getting is Error using horzcat

Dimensions of arrays being concatenated are not consistent.

[Syed Masoom]

the 1 seems to be causing an issue since the rest are a 1x50 double but I don't want to have to create a seperate ones array just to put into my matrix

[madhan ravi]

I suggest you to do MATLAB On-ramp course. You seem to have a problem understanding what a row and a column represent. It’s the first term to know when getting into MATLAB.

[Syed Masoom]

I would like to have it output as a 50x4 matrix with the first column being just 1s. the answer you posted results in a 1x151 double.

[madhan ravi]

 A = x(:) .^ (0:3)

[Syed Masoom]

thank you, could you post that as your answer so i can accept it?

Answer 2

[Steven Lord]

madhan ravi has told you how to do this but I want to explain why your original approach didn't work.

If x is a column vector with 50 elements it has 50 rows (if it were a 1x50 array it would be a row vector.) The number 1 has 1 row. You can't horizontally concatenate an array with one row and an array with 50 rows and have them form a rectangular array as you can see here:

bar([1 2], [1 50])

You could make that 1 an array with the same number of rows as x:

x = (1:10).';
A1 = [ones(size(x)), x, x.^2, x.^3];

Though I'd probably reverse the order of the columns to match the convention of functions like polyfit and polyval.

A2 = x.^(3:-1:0)