delete one row from a matrix

2.49.1 Mathematica
2.49.2 Matlab
2.49.3 Maple

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

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

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

Out[81]= {{1,2,3}, 
          {7,8,9}}

or a little longer solution using Pick

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

Out[70]= {{1,2,3}, 
          {7,8,9}}

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

A = 
     1     2     3 
     7     8     9

A:=<1,2,3; 
    4,5,6; 
    7,8,9>; 
A:=LinearAlgebra:-DeleteRow(A,2);

     [1  2  3] 
A := [       ] 
     [7  8  9]