# module NumRu::GGraph in vector_on_merdional_section.rb

This file defines additional method of NumRu::GGraph. This method is for drawing vector on merdional sections.

## Index

- module NumRu::GGraph
  - vector_on_merdional_section Draw vector by selecting the first 2 dimensions (with GPhys#first2D) if `gphys` is more than 3D.

## Module Functions

`vector_on_merdional_section(fx, fy, newframe=true, options=nil)`

  Draw vector by selecting the first 2 dimensions (with GPhys#first2D) if `gphys` is more than 3D.

  ARGUMENTS

  - fx (GPhys) : a GPhys whose data is plotted x-componet.
  - fy (GPhys) : a GPhys whose data is plotted y-componet.
  - newframe (true/false) : if true, calls fig, axes, title, and annotate internally; if false, only the poly-line is drawn (overlaid to the exiting figure).

  - options (Hash) : options to change the default behavior if specified. It is a Hash with option names (String) as keys and their values. Options are interpreted by a NumRu::Misc::KeywordOptAutoHelp, so you can shorten the keys (by omitting tails) as long as it is unambiguous.

        option name     default value # description:
        "title"         nil           # Title of the figure(if nil, internally
                                      # determined)
        "annotate"      true          # if false, do not put texts on the right
                                      # margin even when newframe==true
        "transpose"     false         # if true, exchange x and y axes
        "flow_vect"     true          # If true, use DCLExt::flow_vect to draw
                                      # vectors; otherwise, DCL::ugvect is used
        "xintv"         1             # (Effective only if flow_vect) interval
                                      # sampling in x of data
        "yintv"         1             # (Effective only if flow_vect) interval
                                      # of data sampling in y
        "factor"        1.0           # (Effective only if flow_vect) scaling
                                      # factor to strech/reduce the arrow
                                      # lengths.
        "use_before_scale"            #
                        false         #(Effective only unless flow_vect) If true,
                                      # use scale factor before vector.
        "unit_vect"     false         # Show the unit vector
        "max_unit_vect" false         # (Effective only if flow_vect &&
                                      # unit_vect) If true, use the maximum
                                      # arrows to scale the unit vector;
                                      # otherwise, normalize in V coordinate.

  RETURN VALUE

  - nil