Combinations¶ ↑

Contents:

Combination allocation¶ ↑

GSL::Combination.alloc(n, k)

These create a new combination with parameters n, k. The combination is not initialized and its elements are undefined. Use the method GSL::Combination.calloc if you want to create a combination which is initialized to the lexicographically first combination.

GSL::Combination.calloc(n, k)

This creates a new combination with parameters n, k and initializes it to the lexicographically first combination.

Methods¶ ↑

GSL::Combination#init_first

This method initializes the combination self to the lexicographically first combination, i.e. (0,1,2,…,k-1).

GSL::Combination#init_last

This method initializes the combination self to the lexicographically last combination, i.e. (n-k,n-k+1,…,n-1).

Accessing combination elements¶ ↑

GSL::Combination#get(i)
GSL::Combination#[i]

This returns the value of the i-th element of the combination self.

Combination properties¶ ↑

GSL::Combination#n

Returns the n parameter of the combination self.

GSL::Combination#k

Returns the k parameter of the combination self.

GSL::Combination#data

Returns the vector of elements in the combination self.

GSL::Combination#valid

This method checks that the combination self is valid. The k elements should contain numbers from range 0 .. n-1, each number at most once. The numbers have to be in increasing order.

GSL::Combination#valid?

Thie returns true if the combination is valid, and false otherwise.

Combination functions¶ ↑

GSL::Combination#next

This method advances the combination self to the next combination in lexicographic order and returns GSL::SUCCESS. If no further combinations are available it returns GSL::FAILURE and leaves self unmodified. Starting with the first combination and repeatedly applying this function will iterate through all possible combinations of a given order.

GSL::Combination#prev

This method steps backwards from the combination self to the previous combination in lexicographic order, returning GSL::SUCCESS. If no previous combination is available it returns GSL::FAILURE and leaves self unmodified.

Reading and writing combinations¶ ↑

GSL::Combination#fwrite(filename)
GSL::Combination#fwrite(io)
GSL::Combination#fread(filename)
GSL::Combination#fread(io)
GSL::Combination#fprintf(filename, format = “%u”)
GSL::Combination#fprintf(io, format = “%u”)
GSL::Combination#fscanf(filename)
GSL::Combination#fscanf(io)

Example¶ ↑

#!/usr/bin/env ruby
require("gsl")

printf("All subsets of {0,1,2,3} by size:\n") ;
for i in 0...4 do
  c = GSL::Combination.calloc(4, i);
  begin
    printf("{");
    c.fprintf(STDOUT, " %u");
    printf(" }\n");
  end while c.next == GSL::SUCCESS
end

Reference index top