###
Arguments

####
Z

An array containing the surface value at each point. If the data are regularly gridded in *
R*
and *
Theta*
, *
Z*
is a two dimensional array, where *
Zi,j*
has a radius of *
Ri*
and an azimuth of *
Thetaj*
. If the data are irregularly-gridded, *
Ri*
and *
Thetai*
contain the radius and azimuth of each *
Zi*
. Note that the ordering of the elements in the array *
Z*
is opposite that used by the POLAR_CONTOUR routine.

####
R

The radius. If the data are regularly gridded in *
R*
and *
Theta*
, *
Zi,j*
has a radius of *
Ri*
. If the data are irregularly-gridded, *
R*
must have the same number of elements as *
Z*
, and contains the radius of each point.

####
Theta

The azimuth, in radians. If the data are regularly gridded in *
R*
and *
Theta*
, *
Zi,j*
has an azimuth of *
Thetaj*
. If the data are irregularly-gridded, *
Theta *
must have the same number of elements as *
Z*
, and contains the azimuth of each point.

###
Keywords

####
GRID

Set this keyword to indicate that *
Z*
is regularly gridded in *
R*
and *
Theta*
.

####
SPACING

A two element vector containing the desired grid spacing of the resulting array in *
x*
and *
y*
. If omitted, the grid will be approximately 51 by 51.

####
BOUNDS

A four element vector, [*
x*
_{
0}
, *
y*
_{
0}
, *
x*
_{
1}
, *
y*
_{
1}
], containing the limits of the *
xy*
grid of the resulting array. If omitted, the extent of input data sets the limits of the grid.

####
QUINTIC

Set this keyword to use quintic interpolation, which is slower but smoother than the default linear interpolation.

####
MISSING

Use this keyword to specify a value to use for areas within the grid but not within the convex hull of the data points. The default is 0.0.

###
Example

R = FINDGEN(50) / 50.0

THETA = FINDGEN(50) * (2 * !PI / 50.0)

Z = R # SIN(THETA)

SURFACE, POLAR_SURFACE(Z, R, THETA, /GRID)