
plvect: Vector plot 

DESCRIPTION:

    Draws a vector plot of the vector (
    u[
    nx][
    ny],
    v[
    nx][
    ny]). The scaling factor for the vectors is given by scale. A
    transformation routine pointed to by pltr with a pointer pltr_data for
    additional data required by the transformation routine is used to map
    indices within the array to the world coordinates. The style of the
    vector arrow may be set using plsvect. 

SYNOPSIS:

plvect(u, v, nx, ny, scale, pltr, pltr_data)

ARGUMENTS:

    u, v (PLFLT **, input) :    Pointers to a pair of vectored
    two-dimensional arrays containing the x and y components of the
    vector data to be plotted. 

    nx, ny (PLINT, input) :    Physical dimensions of the arrays u and v. 

    scale (PLFLT, input) :    Parameter to control the scaling factor of
    the vectors for plotting. If scale = 0 then the scaling factor is
    automatically calculated for the data. If scale < 0 then the
    scaling factor is automatically calculated for the data and then
    multiplied by -
    scale. If scale > 0 then the scaling factor is set to scale. 

    pltr (void (*) (PLFLT, PLFLT, PLFLT *, PLFLT *, PLPointer) , input) : 
      Pointer to function that defines transformation between indices
    in array z and the world coordinates (C only).    Transformation
    functions are provided in the PLplot library: pltr0 for identity
    mapping, and pltr1 and pltr2 for arbitrary mappings respectively
    defined by one- and two-dimensional arrays.  In addition,
    user-supplied routines for the transformation can be used as well.
     Examples of all of these approaches are given in the PLplot
    documentation. The transformation function should have the form
    given by any of pltr0, pltr1, or pltr2. 

    pltr_data (PLPointer, input) :    Extra parameter to help pass
    information to pltr0, pltr1, pltr2, or whatever routine that is
    externally supplied. 
