restart;In this code "add" is a trouble.
A := Matrix([[1, 2, 1, 3], [1, 1, 2, 1], [1, -2, 5, -11]]);
cs := LinearAlgebra:-ColumnSpace(A);
cnames := [seq(c || j, j = 1 .. numelems(cs))];
cvals := seq(solve([entries(A[() .. (), k] -~ add(`*`~(cnames, cs)), 'nolist')], cnames)[], k = 1 .. op([1, 2], A));
seq(add*rhs~(cvals[k]) *~ cs, k = 1 .. op([1, 2], A));
add does not play its role. Why. Thank you.

I try to find kernel and image of a application whose i know the matrix.
restart;
with(LinearAlgebra);
A := Matrix([[1, 1, 1, -1], [-1, 1, -1, -1], [1, -1, -1, -1], [-1, -1, 1, 3]]);
k := op(NullSpace(A));#kernel
MatrixVectorMultiply(A, k);#check
C := op(ColumnSpace(A));
X := <x, y, z, t>;
F := MatrixVectorMultiply(A, X) - a*C[1] - b*C[2] - c*C[2];
G := op(convert(F, list));
solve({seq(G[i] = 0, i = 1 .. 4)}, {a, b, c}); why there is no solution ? Thank you.

How is the matrix of the affinity of base the plan of equation x+2*y-z=1, of direction u <1,0,-1>and of ratio 2 determined? Thank you.

How to know the internal procedures of Maple for instance : taylor or laurent ? Thank you.

I don't know how overcoming this error . Thank you. MyPackage := module() export f1, f2; local loc1; option package; f1 := proc() loc1 end proc; f2 := proc( v ) loc1 := v end proc; loc1 := 2; end module: savelib('MyPackage'); Error, cannot open archive, C:\Program Files\Maple 2018\lib, for writing. restart; with(MyPackage); Error, invalid input: with expects its 1st argument, pname, to be of type {`module`, package}, but received MyPackage