delete one column from a matrix

2.50.1 Mathematica
2.50.2 Matlab
2.50.3 Maple

Example, Given the folowing 2D matrix \(A\) delete say the second column

\(\begin {pmatrix} 1 & 2 & 3\\ 4 & 5 & 6\\ 7 & 8 & 9 \end {pmatrix}\)

mat={{1,2,3}, 
     {4,5,6}, 
     {7,8,9}}; 
 
mat[[All,2]]=Sequence[]; 
mat

Out[93]= {{1,3}, 
          {4,6}, 
          {7,9}}

or a little longer solution using Pick

{nRow,nCol}=Dimensions[mat]; 
mask=Table[True,{nRow},{nCol}]; 
mask[[All,2]]=False; 
mat=Pick[mat,mask]; 
mat

Out[98]= {{1,3}, 
          {4,6}, 
          {7,9}}

A=[1 2 3;4 5 6;7 8 9]; 
A(:,2)=[]

A:=Matrix([[1,2,3],[4,5,6],[7,8,9]]); 
A:=LinearAlgebra:-DeleteColumn(A,2);

\[ \left [ \begin {array}{cc} 1&3\\ \noalign {\medskip }4&6 \\ \noalign {\medskip }7&9\end {array} \right ] \]