lodo.spad line 55 [edit on github]
LinearOrdinaryDifferentialOperatorsOps provides symmetric products and sums for linear ordinary differential operators.
directSum(a, b, D) computes an operator c of minimal order such that the nullspace of c is generated by all the sums of a solution of a by a solution of b. D is the derivation to use.
symmetricPower(a, n, D) computes an operator c of minimal order such that the nullspace of c is generated by all the products of n solutions of a. D is the derivation to use.
symmetricProduct(a, b, D) computes an operator c of minimal order such that the nullspace of c is generated by all the products of a solution of a by a solution of b. D is the derivation to use.