area.tcl

This example shows how to build surface by approximating areas with constant real numbers. In this example 5 different areas were used. Suppose that for three of them (area1, area3 and area5) exact values are known, for other two (area2 and area4) - only approximative values. So, we want to build surface, which approximates as exactly as possible values for areas 1,3 and 5, and "not so exactly" for areas 2 and 4.

See also:

area, area_add, completer

To produce this surface we should do the following things:

• load areas to the memory
• create equidistant grid
• set some additional parameters (tolerance, map_name)
• create sequence of gridding rules (how to use areas and space between them)
• run Description of the surfit gridding algorithm algorithm
• save results to file

Here is the image of the resulting surface (green colour for areas 1,3 and 5, red colour for areas 2 and 4):

Pic 1. Surface built from areas

This result was obtained with "examples/surfit/curvs/area.tcl" script.

#
# This script was generated with funner v2.1beta (www.gridding.info)

# 
# load plugins
# 
load libsurfit[info sharedlibextension]

# remove all previous data and gridding rules
clear_data 

# set name of surface
set map_name "map_area" 

# set tolerance for cg solver
set tol 5.01187e-006 

##
## load initial data 
##
 
# load area from text file 
area_read "area1.txt" "area1"  
 
# load area from text file 
area_read "area2.txt" "area2"  
 
# load area from text file 
area_read "area3.txt" "area3"  
 
# load area from text file 
area_read "area4.txt" "area4"  
 
# load area from text file 
area_read "area5.txt" "area5"  
 
##
## construct grid 
##
grid_get -12 12 0.2 -12 12 0.2 
 
##
## create gridding rules
##

# resulting surface in area = value... 
area 10 "area1"  

# resulting surface in area = value... 
area 30 "area3"  

# resulting surface in area = value... 
area undef "area5"  

# resulting surface should tend to be constant or plane 
completer 1 1.6  

# add "resulting surface in area = value..." with weight 
area_add 20 0.07 "area2"  

# add "resulting surface in area = value..." with weight 
area_add 40 0.07 "area4"  

##
## run gridding algorithm
##
surfit 

##
## save results 
##

# unload grid from memory
grid_unload 

# save surface to surfit datafile 
surf_save "area.dat" "map_area" 

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surfit: open source gridding and contouring software.