
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 mode
subsop([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]].