void lcontour (fun, x, nx, y, ny, level, nlevel, lnstyle,labint, format) CNTPLT.C Level 3
float (*fun)(float float) A user-defined function which returns z = fun(x, y).
float *x The x vector.
int nx The number of x values.
float *y The y vector.
int ny The number of y values.
float *level A vector of level contour values arranged in increasing order.
int nlevel The number of level contours.
int *lnstyle An array of coded numbers for changing line styles and/or colors for each contour level. See the explanation at the beginning of this section. This specification will not handle the extended GraphiC colors and is retained for compatibility purposes.
 If lnstyle == NULL, the more powerful specification capability of contcolor() will be used (recommended).
int labint Labels are placed on every labint contour. If labint = 0, contour labels are suppressed.
char *format A valid floating-point format for the contour labels.
lcontour() produces level contours for the function fun(x, y). That is, for each level C, the curve fun(x, y) = C is plotted. For best results, the size of the x-y grid squares should be small compared to the length in which fun(x, y) varies significantly.  The level contours are provided by you, so things such as logarithmic level values may be used. Because lcontour() must evaluate the function on each grid point, it can take a long time, especially if the function is complicated and you don't have a math coprocessor.