Calculador de Somatório (simples)

function [p np ntpc npc npi] = parcialcalc(mrk,key,np)
%PARCIALCALC Calculates partial score of questions, UFSC-style.
%   This function calculates the score reached on a certain
%   question, UFSC-style. It uses the following method:
%
%   If NPC > NPI:
%                NP - (NTPC - ( NPC - NPI  ) )
%           P = ------------------------------
%                            NP
%   Else:   P = 0
%
%   Where:
%   P: Final score
%   NP: Number of prepositions (total)
%   NTPC: Number of total correct prepositions
%   NPC: Number of corrects prepositions marked
%   NPI: Number of incorrects prepositions marked
%
%   It does some simple logic manipulations on the numbers
%   after converted it into a binary array.
%
%   Usage:
%
%   parcialcalc(sum,key,np)
%
%   Where:  mrk: the value marked by the person
%           key: the correct value
%           np: number of prepositions within the question
%
%   It returns the following values respectively:
%       [P, NP, NTPC, NPC, NPI]


bit_sum=de2bi(mrk,np);
bit_key=de2bi(key,np);

ntpc=sum(bit_key);

npc=sum(bitand(bit_sum,bit_key));

npi=sum(bitand(bit_sum,bitxor(bit_key,ones(1,np))));

if npc > npi
    p=1-(ntpc-npc+npi)/np;
else
    p=0;
end

end