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[Octave-bug-tracker] [bug #56515] griddatan errors when querying with on
From: |
Kai Torben Ohlhus |
Subject: |
[Octave-bug-tracker] [bug #56515] griddatan errors when querying with only one valid point |
Date: |
Tue, 18 Jun 2019 03:03:03 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.90 Safari/537.36 |
Update of bug #56515 (project octave):
Severity: 3 - Normal => 1 - Wish
Priority: 5 - Normal => 3 - Low
Item Group: Unexpected Error => Feature Request
Status: None => Patch Submitted
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Follow-up Comment #1:
Thank you for the bug report. I noticed, that Matlab R2019a errors for your
example as well:
Error using builtin
QH6154 qhull precision error: initial facet 1 is coplanar with the interior
point
ERRONEOUS FACET:
While executing: | qhull d Qt Qbb Qc
Options selected for Qhull 2010.1 2010/01/14:
run-id 1522627653 delaunay Qtriangulate Qbbound-last Qcoplanar-keep
_pre-merge _zero-centrum Qinterior-keep Pgood _max-width 1
Error-roundoff 1.4e-15 _one-merge 9.7e-15 Visible-distance 2.8e-15
U-coplanar-distance 2.8e-15 Width-outside 5.5e-15 _wide-facet 1.7e-14
The input to qhull appears to be less than 3 dimensional, or a
computation has overflowed.
Qhull could not construct a clearly convex simplex from points:
The center point is coplanar with a facet, or a vertex is coplanar
with a neighboring facet. The maximum round off error for
computing distances is 1.4e-15. The center point, facets and distances
to the center point are as follows:
facet p1 p2 p0 distance= 0
facet p3 p2 p0 distance= 0
facet p3 p1 p0 distance= 0
facet p3 p1 p2 distance= 0
These points either have a maximum or minimum x-coordinate, or
they maximize the determinant for k coordinates. Trial points
are first selected from points that maximize a coordinate.
The min and max coordinates for each dimension are:
0: 0 1 difference= 1
1: 0 1 difference= 1
2: 0 1 difference= 1
If the input should be full dimensional, you have several options that
may determine an initial simplex:
- use 'QJ' to joggle the input and make it full dimensional
- use 'QbB' to scale the points to the unit cube
- use 'QR0' to randomly rotate the input for different maximum points
- use 'Qs' to search all points for the initial simplex
- use 'En' to specify a maximum roundoff error less than 1.4e-15.
- trace execution with 'T3' to see the determinant for each point.
If the input is lower dimensional:
- use 'QJ' to joggle the input and make it full dimensional
- use 'Qbk:0Bk:0' to delete coordinate k from the input. You should
pick the coordinate with the least range. The hull will have the
correct topology.
- determine the flat containing the points, rotate the points
into a coordinate plane, and delete the other coordinates.
- add one or more points to make the input full dimensional.
This is a Delaunay triangulation and the input is co-circular or
co-spherical:
- use 'Qz' to add a point "at infinity" (i.e., above the paraboloid)
- or use 'QJ' to joggle the input and avoid co-circular data
Error in qhullmx
Error in delaunayn (line 101)
t = qhullmx(x', 'd ', opt);
Error in griddatan>linear (line 105)
tri = delaunayn(x);
Error in griddatan (line 89)
yi = linear(x,y,xi,opt);
Thus this item should be treated as feature request.
But I can confirm, that the three line patch of bug #45542 fixes the original
problem. We should concentrate on bug #45542 and fix this item as "side
effect".
_______________________________________________________
Reply to this item at:
<https://savannah.gnu.org/bugs/?56515>
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