sample_field_2d

(./FEM/sample_field_2d.m)

Function Synopsis

outmat=sample_field_2d(fem_grid_struct,nx,ny,Q,box_coords)

Help text

SAMPLE_FIELD_2D Mouse-driven 2-D FEM Field Sampler
   SAMPLE_FIELD_2D is a mouse-driven 2-D field sampler prompts
   the user to draw a box on the current figure, and 
   returns an array of coordinates and interpolated 
   field values.  The input field array can be any number
   of columns wide (scalar, vector, etc.) but must be as
   long as the node coordinate lists in fem_grid_struct.
   I.e., the fields to interpolate will usually come from 
   the FEM domain itself.

  INPUT:  fem_grid_struct - FEM domain structure on which the field
                   to sample is related (from LOADGRID, see FEM_GRID_STRUCT).
          nx,ny  - number of points in the x and y direction at which to 
                   sample the fields Q.  (REQUIRED, INTEGERS)
          Q      - the fields to sample. This array must be the same length as 
                   the node coordinate arrays in the valid fem_grid_struct
                   passed in, but the number of columns is arbitrary.

          box_coords - optional 4x1 vector defining the sample region.  
                       The 4 values are [X1 Y1 X2 Y2], and if defined
                       they take precedence over the mouse-driven facility.

 OUTPUT:  S      - an array containing the sample points and sample values.
                   If nx or ny==1, then S contains the sample points and 
                   sample values in columns.  Otherwise, S is an 
                   [nx X ny X ncol] array, where ncol is the number of
                   columns in the input array Q and the first 2 levels of
                   S are the X and Y coordinates (X=S(:,:,1), Y=S(:,:,2)).
                   Points not located within FEM domain are assigned NaN's 
                   as field values.
 
                   To contour the results in the case where nx and ny > 1, 
                   call MATLAB's contourf routine with S appropriately
                   sampled.  For example:
                   >> contourf(S(:,:,1),S(:,:,2),S(:,:,3))
           
   CALL: S=sample_field_2d(fem_grid_struct,nx,ny,Q)

 Written by Brian O. Blanton
 Summer 1998

Cross-Reference Information

is_valid_struct./FEM/is_valid_struct.m