Method: LogicTools#to_sum_product_array

Defined in:
lib/logic_tools/minimal_column_covers.rb

#to_sum_product_array(product) ⇒ Object

Converts a product of sum to a sum of product.

NOTE: * Both the input are outputs are represented as array of arrays.



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# File 'lib/logic_tools/minimal_column_covers.rb', line 13

def to_sum_product_array(product)
    return product[0].map {|term| [term] } if product.size == 1
    # Generate the initial terms.
    sum = product[0].product(product[1]) 
    sum.each {|term| term.sort!.uniq! }
    sum.uniq!
    # Fill then with each factor to the resulting sum of product.
    # print "sum = #{sum}, product=#{product}\n"
    (2..(product.size-1)).each do |i|
        sum.map! do |term|
            # # print "mapping #{product[i]}\n"
            set = []
            product[i].each do |fact|
                if term.include?(fact) then
                    set << term unless set.include?(term)
                else
                    nterm = term.clone
                    nterm << fact
                    nterm.sort!
                    set << nterm
                end
            end
            set
        end
        sum.flatten!(1)
        # print "then sum=#{sum}\n"
        sum.uniq!
        # print "now sum=#{sum}\n"
        # pid, size = `ps ax -o pid,rss | grep -E "^[[:space:]]*#{$$}"`.strip.split.map(&:to_i)
        # print "memory usage=#{size}\n"
    end
    # print "\n"
    return sum
end