# Documentation of m_vec

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## Function Synopsis

    [hp, ht] = mvec(s, x, y, varargin)  % and color, etc

## Help text

     M_VEC Draws fancy arrows/quiverplots on a map.
        [HP, HT]=M_VEC(S,LONG,LAT,VARARGIN) draws arrows as a patch
        object on a map created by the M_Map package.
          HP: handle to the patch object
          HT: handle to text object if this is a key; see below.
          S:  scale factor, arrow data units per inch.
              It is based on the figure PaperPosition, so be
              sure to set this (e.g. via "landscape" or "portrait")
              before calling m_vec.
          LONG,LAT: longitude, latitude of the arrows
              LONG and LAT must have the same dimensions, but can be
              scalars or vectors; if scalars, multiple arrows can
              be plotted at a single location.
          VARARGIN can consist of any of the following:
            U,V   U,V,C   Z,U,V,C
          followed by optional arrow parameters,
          followed by optional patch parameters.
            U,V are vectors containing the east and north components
                     of the arrows.
            C is an optional colorspec for all arrows, or an
                     array of CData, one value per arrow.
                     Defaults to black.
            Z is a height in axes data units: this is subject
                     to future modification or omission, and
                     is probably not useful now as-is.
          optional arrow parameters: keyword-value pairs, shown
                     here with default values:
             'headangle',60     degrees: angle of arrow tip
             'headwidth',NaN    points: direct specification of
                                    width, instead of headangle
             'headlength',5     points: length of tip; set to 0
                                    to omit arrowhead entirely
             'shaftwidth',1     points: width of arrow shaft
             'centered', 'no'   'yes' to make x,y the arrow
                                    center instead of its tail
             'key', ''          make a labelled horizontal arrow
                                    if the string is not empty;
                                    then the string labels the
                                    arrow, and the second argument
                                    returned, ht, is the handle of
                                    the string.
          optional patch parameters: any valid patch properties
             may be specified here; they are passed directly
             to the patch function.

        M_VEC called without any parameters generates a demonstration plot.

## Cross-Reference Information

This function calls | This function is called by
--- | ---
m_coast m_grid m_ll2xy m_proj | current_figure grid_current_plot m_demo

Pierre-Michel THEVENY <theveny@dt.insu.cnrs.fr>