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diff --git a/src/Alpha_complex/utilities/README b/src/Alpha_complex/utilities/README new file mode 100644 index 00000000..30e1b187 --- /dev/null +++ b/src/Alpha_complex/utilities/README @@ -0,0 +1,131 @@ +# Alpha_complex # + +## `alpha_complex_3d_persistence` ## +This program computes the persistent homology with coefficient field Z/pZ of the 3D alpha complex built from a 3D point cloud. The output diagram contains one bar per line, written with the convention: + +`p dim b d` + +where `dim` is the dimension of the homological feature, `b` and `d` are respectively the birth and death of the feature, and `p` is the characteristic of the field *Z/pZ* used for homology coefficients (`p = p1*...*pr` is the product of prime numbers *pi* such that the homology feature exists in homology with *Z/piZ* coefficients). + +**Usage** +`alpha_complex_3d_persistence <input OFF file> <p> <min_persistence>` +where +`<input OFF file>` is the path to the input point cloud in OFF format. +`<p>` is the characteristic p of the coefficient field *Z/pZ* for computing homology. It must be a stricly positive integer. +`<min_persistence>` is the minimal lifetime of homology feature to be recorded. Enter a negative value to see zero length intervals. It must be a floating-point number >= -1. + +**Example** +`alpha_complex_3d_persistence ../../data/points/tore3D_300.off 2 0.45` + +outputs: +``` +Simplex_tree dim: 3 +2 0 0 inf +2 1 0.0682162 1.0001 +2 1 0.0934117 1.00003 +2 2 0.56444 1.03938 +``` + +Here we retrieve expected Betti numbers on a tore 3D: +``` +Betti numbers[0] = 1 +Betti numbers[1] = 2 +Betti numbers[2] = 1 +``` + +N.B.: +* `alpha_complex_3d_persistence` only accepts OFF files in dimension 3. +* Filtration values are alpha square values. + + + + +## `periodic_alpha_complex_3d_persistence` ## +This program computes the persistent homology with coefficient field Z/pZ of the 3D periodic alpha complex built from a 3D point cloud. The output diagram contains one bar per line, written with the convention: + +`p dim b d` + +where `dim` is the dimension of the homological feature, `b` and `d` are respectively the birth and death of the feature, and `p` is the characteristic of the field *Z/pZ* used for homology coefficients (`p = p1*...*pr` is the product of prime numbers *pi* such that the homology feature exists in homology with *Z/piZ* coefficients). + +**Usage** +`periodic_alpha_complex_3d_persistence <input OFF file> <p> <min_persistence>` +where +`<input OFF file>` is the path to the input point cloud in OFF format. +`<p>` is the characteristic p of the coefficient field *Z/pZ* for computing homology. It must be a stricly positive integer. +`<min_persistence>` is the minimal lifetime of homology feature to be recorded. Enter a negative value to see zero length intervals. It must be a floating-point number >= -1. + +**Example** +`periodic_alpha_complex_3d_persistence ../../data/points/grid_10_10_10_in_0_1.off ../../data/points/iso_cuboid_3_in_0_1.txt 3 1.0` + +outputs: +``` +Periodic Delaunay computed. +Simplex_tree dim: 3 +3 0 0 inf +3 1 0.0025 inf +3 1 0.0025 inf +3 1 0.0025 inf +3 2 0.005 inf +3 2 0.005 inf +3 2 0.005 inf +3 3 0.0075 inf +``` + +Here we retrieve expected Betti numbers on an 3D iso-oriented cuboids: +``` +Betti numbers[0] = 1 +Betti numbers[1] = 3 +Betti numbers[2] = 3 +Betti numbers[3] = 1 +``` + +N.B.: +* `periodic_alpha_complex_3d_persistence` only accepts OFF files in dimension 3. +* In this example, the periodic cube is hard coded to { x = [0,1]; y = [0,1]; z = [0,1] } +* Filtration values are alpha square values. + + + + + +## `alpha_complex_persistence` ## +This program computes the persistent homology with coefficient field Z/pZ of the dD alpha complex built from a dD point cloud. The output diagram contains one bar per line, written with the convention: + +`p dim b d` + +where `dim` is the dimension of the homological feature, `b` and `d` are respectively the birth and death of the feature, and `p` is the characteristic of the field *Z/pZ* used for homology coefficients (`p = p1*...*pr` is the product of prime numbers pi such that the homology feature exists in homology with Z/piZ coefficients). + +**Usage** +`alpha_complex_persistence [options] <OFF input file>` + +**Allowed options** + +* `-h [ --help ]` Produce help message +* `-o [ --output-file ]` Name of file in which the persistence diagram is written. By default, print in std::cout. +* `-r [ --max-alpha-square-value ]` (default = inf) Maximal alpha square value for the Alpha complex construction. +* `-p [ --field-charac ]` (default = 11) Characteristic p of the coefficient field Z/pZ for computing homology. +* `-m [ --min-persistence ]` (default = 0) Minimal lifetime of homology feature to be recorded. Enter a negative value to see zero length intervals. + +**Example** +`alpha_complex_persistence -r 32 -p 2 -m 0.45 ../../data/points/tore3D_300.off` + +outputs: +``` +Alpha complex is of dimension 3 - 9273 simplices - 300 vertices. +Simplex_tree dim: 3 +2 0 0 inf +2 1 0.0682162 1.0001 +2 1 0.0934117 1.00003 +2 2 0.56444 1.03938 +``` + +Here we retrieve expected Betti numbers on a tore 3D: +``` +Betti numbers[0] = 1 +Betti numbers[1] = 2 +Betti numbers[2] = 1 +``` + +N.B.: +* `alpha_complex_persistence` only accepts OFF files in dimension d. +* Filtration values are alpha square values. |