3.5.5 Type conversion and casting

Type conversion

Assignments convert the type of the right-hand side to the type of the left-hand side of the assignment, if possible. Operators and functions which require certain types of operands can also implicitly convert the type of an expression. It is, for example, possible to multiply a polynomial by an integer because the integer is automatically converted to a polynomial. Type conversions do not act transitively. Possible conversions are:

Type casting

An expression can be casted to another type by using a type cast expression:
type ( expression ).

Possible type casts are:

	to	from
	ideal	expression lists of int, number, poly
	ideal	int, matrix, module, number, poly, vector
	int	number, poly
	intvec	expression lists of int, intmat
	intmat	intvec (see intmat type cast)
	list	expression lists of any type
	matrix	module, ideal, vector, matrix. There are two forms to convert something to a matrix: if matrix( expression ) is used then the size of the matrix is determined by the size of expression. But matrix( expression , m , n ) may also be used - the result is a matrix (see matrix type cast)
	module	expression lists of int, number, poly, vector
	module	ideal, matrix, vector
	number	poly
	poly	int, number
	string	any type (see string type cast)

Example:

  ring r=0,x,(c,dp);
  number(3x);
→ 0
  number(poly(3));
→ 3
  ideal i=1,2,3,4,5,6;
  print(matrix(i));
→ 1,2,3,4,5,6
  print(matrix(i,3,2));
→ 1,2,
→ 3,4,
→ 5,6 
  vector v=[1,2];
  print(matrix(v));
→ 1,
→ 2 
  module(matrix(i,3,2));
→ _[1]=[1,3,5]
→ _[2]=[2,4,6]