NAME
    swap - swap values of two variables

SYNOPSIS
    swap(x,y)

TYPES
    x, y	lvalues, any type

    return	null value

DESCRIPTION
   swap(x,y) assigns the value of x to a temporary location, temp say,
   assigns the value of x to y, and then assigns the value at temp to y.

   swap(x,y) should not be used if the current value of one of the
   variables is a component of the value of the other; for example, after:

	 A = list(1,2,3); swap(A, A[[1]]);

   A will have the value 2, but a three-member list remains in memory
   with no method within calc of recalling the list or freeing the
   memory used.

EXAMPLE
   > x = 3/4; y = "abc"; print x, y, swap(x,y), x, y
   .75 abc  abc .75

   > A = list(1,2,3); mat B[3] = {4,5,6}; swap(A[[1]], B[1]); print A[[1]], B[1]
   5 2

LIMITS
    none

LIBRARY
    none

SEE ALSO
    assign