You can find this a recurring topic. You can fix the file trisRI2D.c &
rebuild or build everything from cvs. What follows is copied verbatim from
an earlier append:
>Yes, there was a bug introduced to Map and subsequently fixed Apr 17 2000
, see
>
http://opendx.watson.ibm.com/cgi-bin/dx/cvsweb/dx/src/exec/libdx/trisRI2D.c
>There is no "4.1.1" mark in cvs and no "4.1.1" tarball, so I can't tell
you if a
>binary labelled 4.1.1 will have the bug or not. Compare dates, perhaps.
>Building fresh from our cvs would definitely address the problem.
"Mr. Roman Putanowicz" wrote:
> Hi,
>
> Either I miss something or I encountered strange behavior of Map module
> :-(.
>
> The problem is as follows:
> We have scalar function of two variables f = f(x,y);
> Let assume that
> f(x,y)= x^2 + y^2 and x in [-0.5,1.0], y in [-0.5, 1.5]
> Draw the profile of function 'f' along a line parallel to 'y'-axis
> passing through specified point [x0, y0].
>
> The function is given by the set of points on regular rectangular grid.
>
> I solved the problem in the following steps:
> 1) read in the data
> 2) create line grid passing through [x0, y0] and perpendicular to y
> 3) Map the read data on the line grid
> 4) Create 2D plot of data on line
>
> Below I included the script implementing the steps.
>
> It works fine except for cases when the grid line passes exactly
> through one of the rectangular grid lines (in other words when
> point [x0, y0] is one of the grid points on which function f has
> been specified)!!!! This is exactly opposite I would expect.
> What's more if I only slightly move my [x0, y0] point it produces
> again correct results.
>
> Any ideas what is wrong ?
> (I'm running Data Explorer version 4.0.1 on Linux box).
>
> To make it possible to reproduce the behavior I included three short
> files:
> 1) dx script
> 2) general array importer header file
> 3) awk script to produce data file
>
> Regards
> Roman Putanowicz
> [EMAIL PROTECTED]
>
> 1)
> The correct results are produced for instance for point [0.96 0.5]
> The wrong result are produced for point [0.97 0.5]
> ----------------------- 8<----------8<----------------------------
> data = Import ("header.general");
> // Create line parallel to 'y' axis
> // set point to [0.96 0.5] to see the correct profile
> // set point to [0.97 0.5] to see the incorrect profile
> line = Grid ([0.97 0.5],"line", [0 1], {30});
> data = Map (line, data);
> data = Mark (data, "positions");
> data = Compute ("$0.y", data);
> data = Unmark (data, "positions");
> data = Color(data, "medium turquoise");
> data = Options (data, "mark", "triangle", "mark every", 3, "label",
> "fluid speed");
> image = Plot(data, {"y" "fluid speed"});
> camera = AutoCamera (image);
> image = Render (image, camera);
> Display (image);
> ------------------------ 8<-- cut here and save as 'plotdata' ------
>
> 2)
> -------------------------8<--------8<------------------------------
> file = data.lis
> grid = lines 1
> format = text
> field = locations, fun_value
> structure = 2-vector, scalar
> layout = 0, 12, 1, 12
> interleaving = field
> end
> ------------------------8<-- cut here and save as 'header.general'
>
> 3)
> ------------------------8<--------8<------------------------------
> BEGIN {
> n = 100
> xl = 1.5;
> yl = 2.0;
> dx = xl/n;
> dy = yl/n;
> y = -0.5
> # create line of comment and line with grid size
> printf ("# quadratic function x^2+y^2 in domain x=[-0.5,1.0]
> y=[-0.5,2.0]\n")
> printf ("%d %d\n", n+1, n+1)
> for (i=0; i<n+1; i++) {
> x = -0.5
> for (j=0; j<n+1; j++) {
> printf ("%12.7f%12.7f %12.7f\n", x, y, x*x+y*y)
> x = x+dx;
> }
> y = y+dy;
> }
> }
> ------------------------------8<-- cut here and save as makedata.awk
>
> (If you are working on decent Unix/Linux :-)
> To produce data file run the following command:
> awk -f makedata.awk > data.lis
>
> To run dx script type
> dx -script
>
> and then
> include "plotdata"
