reads two 2-D grid files which represents the x- and y-components of a vector field and produces a vector field plot by drawing vectors with orientation and length according to the information in the files. Alternatively, polar coordinate components may be used (r, theta). Selects the map projection. Scale is UNIT/degree, 1:xxxxx, or width in UNIT (upper case modifier). UNIT is cm, inch, or m, depending on the stand for global domain (0/360 and -180/+180 in longitude respectively, with -90/+90 in latitude). Alternatively, specify the name of an existing grid file and the settings (and grid spacing, if applicable) are copied from the grid. For calendar time coordinates you may either give (a) relative time (relative to the selected string must be of the form hh:mm:ss[.xxx]. The use of delimiters and their type and positions must be exactly as indicated (however, input, output and plot formats are customizable, see , the user may specify the justification of the stamp and where the stamp should fall on the page relative to lower left corner of the plot. For example, BL/0/0 will align the lower left corner of the time stamp with the lower left corner of the plot. Optionally, append a Set pen attributes used for vector outlines [Default: width = 0.25p, color = black, texture = solid]. (See SPECIFYING PENS below). to make this apply only to input or output [Default applies to both]. Give one or more columns (or column ranges) separated by commas. Append of lines, areas and patterns can be specified by a valid color name, by a gray shade (in the range 0−255), by a decimal color code (r/g/b, each in range 0−255, h-s-v, ranges 0−360, 0−1, 0−1, or c/m/y/k, each in range 0−1), or by a hexadecimal color code (#rrggbb, as used in HTML). See the is able to recognize many of the commonly used grid file formats, as well as the precision, scale and offset of the values contained in the grid file. When in your shell program by putting a backslash in front of it, or by placing the filename and suffix between quotes or double quotes. See (1) and Section 4.18 of the GMT Technical Reference and Cookbook for more information, particularly on how to read splices of 3-, 4-, or 5-dimensional grids. To draw the vector field given by the files r.grd and theta.grd on a linear plot with scale 5 cm per data unit, using vector rather than stick plot, and scale vector magnitudes so that 10 units equal 1 inch, run Source.