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Copyright © 1995, 1997 The Geometry Center, Minneapolis MN
Synopsis Main Output Formats Geomview Print Qhull Precision Trace
Option 'Tv' checks the topological structure, convexity, and point inclusion. If precision problems occurred, facet convexity is tested whether or not 'Tv' is selected. Option 'Tv' does not check point inclusion if forcing output with 'Po', or if 'Q5' is set.
The convex hull of a set of points is the smallest polytope that includes the points. Option 'Tv' tests point inclusion. Qhull verifies that all points are below all outer planes (facet->maxoutside). Point inclusion is exhaustive if merging or if the facet-point product is small enough; otherwise Qhull verifies each point with a directed search (qh_findbest). To force an exhaustive test when using option 'C-0' (default), use 'C-1e-30' instead.
Point inclusion testing occurs after producing output. It prints a message to stderr unless option 'Pp' is used. This allows the user to interrupt Qhull without changing the output.
Qhull includes frequent checks of its data structures. Option 'Tc' will catch most inconsistency errors. It is slow and should not be used for production runs. Option 'Tv' performs the same checks after the hull is constructed.
Option 'Ts' collects statistics and prints them to stderr. For Delaunay triangulations, the angle statistics are restricted to the lower or upper envelope.
Redirect stderr to stdout.
Option 'TFn' reports progress whenever more than n facets are created. The test occurs just before adding a new point to the hull. During post-merging, 'TFn' reports progress after more than n/2 merges.
Qhull adds one point at a time to the convex hull. See how Qhull adds a point. Option 'TV-n' stops Qhull just before adding a new point. Output shows the hull at this time.
Qhull builds a cone from the point to its horizon facets. Option 'TCn' stops Qhull just after building the cone. The output for 'f' includes the cone and the old hull.'.
Option 'TVn' stops Qhull after it has added point n. Output shows the hull at this time.
Qhull includes full execution tracing. 'T-1' traces events. 'T1' traces the overall execution of the program. 'T2' and 'T3' trace overall execution and geometric and topological events. 'T4' traces the algorithm. 'T5' includes information about memory allocation and Gaussian elimination. 'T1' is useful for logging progress of Qhull in high dimensions.
Option 'Tn' can produce large amounts of output. Use options 'TPn' and 'TMn' to selectively turn on tracing. Since all errors report the last processed point, option 'TPn' is particularly useful.
This reduces the output size when tracing. It is the normal method to determine the cause of a Qhull error. All Qhull errors report the last point added.
Turn on tracing at n'th merge.
Along with TMn, this option allows the user to determine the cause of a wide merge.
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Comments to: qhull@geom.umn.edu
Created: Sept. 25, 1995 --- Last modified: see top