# PGPLOT Module: PGCONT -- contour map of a 2D data array (contour-following)

SUBROUTINE PGCONT (A, IDIM, JDIM, I1, I2, J1, J2, C, NC, TR)

INTEGER IDIM, JDIM, I1, J1, I2, J2, NC

REAL A(IDIM,JDIM), C(*), TR(6)

Draw a contour map of an array. The map is truncated if

necessary at the boundaries of the viewport. Each contour line

is drawn with the current line attributes (color index, style, and

width); except that if argument NC is positive (see below), the line

style is set by PGCONT to 1 (solid) for positive contours or 2

(dashed) for negative contours.

**Arguments**

A (input) : data array.

IDIM (input) : first dimension of A.

JDIM (input) : second dimension of A.

I1, I2 (input) : range of first index to be contoured (inclusive).

J1, J2 (input) : range of second index to be contoured (inclusive).

C (input) : array of NC contour levels; dimension at least NC.

NC (input) : +/- number of contour levels (less than or equal

to dimension of C). If NC is positive, it is the

number of contour levels, and the line-style is

chosen automatically as described above. If NC is

negative, it is minus the number of contour

levels, and the current setting of line-style is

used for all the contours.

TR (input) : array defining a transformation between the I,J

grid of the array and the world coordinates.

The world coordinates of the array point A(I,J)

are given by:

X = TR(1) + TR(2)*I + TR(3)*J

Y = TR(4) + TR(5)*I + TR(6)*J

Usually TR(3) and TR(5) are zero - unless the

coordinate transformation involves a rotation or

shear.