- 
In Xcas mode, the first index is 0
 subsop has two (resp three) arguments: a matrix A and an 
equality [r,c]=v (resp a matrix A, a list of index [r,c],
a value v).
 subsop replaces the element A[r,c] by v.
 Input in Xcas mode :subsop([[4,5],[2,6]],[1,0]=3) Or :subsop([[4,5],[2,6]],[1,0],3) Output :[[4,5],[3,6]] Remark
 If the matrix is stored in a variable, for example 
A:=[[4,5],[2,6]], it is easier to input A[1,0]:=3
which modifies A into the matrix
 [[4,5],[3,6]].
- In Mupad, TI mode, the first index is 1
 subsop has two (resp three) arguments: a matrix A and an 
equality [r,c]=v (resp a matrix A, a list of index [r,c],
a value v).
 subsop replaces the element A[r,c] by v.
 Input in Mupad, TI mode :subsop([[4,5],[2,6]],[2,1]=3) Or :subsop([[4,5],[2,6]],[2,1],3) Output :[[4,5],[3,6]] Remark
 If the matrix is stored in a variable, for example 
A:=[[4,5],[2,6]], it is easier to input A[2,1]:=3 which
modifies A into the matrix
 [[4,5],[3,6]].
- In Maple mode, 
the arguments are permuted and the first index is 1
 subsop has two arguments: an equality [r,c]=v and a matrix 
A.
 subsop replaces the element A[r,c] by v.
 Input in Maple modesubsop([2,1]=3,[[4,5],[2,6]]) Output :[[4,5],[3,6]] Remark
 If the matrix is stored in a variable, for example 
A:=[[4,5],[2,6]], it is easier to input A[2,1]:=3 which
modifies A into the matrix
 [[4,5],[3,6]].