错误：水平尺寸不匹配（4x4 与 1x4）

Question

Why there is an error in the below code? I have tried to convert a row of the matrix B into a column of it.

B=[B 20*B(:,1)]
B =

      1      2      3     20
     10     20     30    200
      7      8      9    140
    100    200    300   2000

B=[B,B(1,:)]

error: horizontal dimensions mismatch (4x4 vs 1x4)

Answer 1

B(1,:) is 1x4 as dimensions

   1      2      3     20

While B is 4x4

      1      2      3     20
     10     20     30    200
      7      8      9    140
    100    200    300   2000

and you are asking Octave to make a matrix like

      1      2      3     20       1      2      3     20
     10     20     30    200
      7      8      9    140
    100    200    300   2000

that clearly does not work.