Name

---

      MAKE_2D

Purpose

---

      Change from 1-d indexing to 2-d indexing

Explanation

---

      Convert an N element X vector, and an M element Y vector, into
      N x M arrays giving all possible combination of X and Y pairs.
      Useful for obtaining the X and Y positions of each element of
      a regular grid.

Calling Sequence

---

      MAKE_2D, X, Y, [ XX, YY ]

Inputs

---

      X - N element vector of X positions
      Y - M element vector of Y positions

Outputs

---

      XX - N x M element array giving the X position at each pixel
      YY - N x M element array giving the Y position of each pixel
              If only 2 parameters are supplied then X and Y will be
              updated to contain the output arrays

Example

---

      To obtain the X and Y position of each element of a 30 x 15 array
      IDL> x = indgen(30) & y = indgen(15)
      IDL> make_2d, x, y

Revision History

---

      Written, Wayne Landsman ST Systems Co. May, 1988
      Added /NOZERO keyword W. Landsman Mar, 1991
      Converted to IDL V5.0 W. Landsman September 1997
      Improved speed P. Broos July 2000