[poincare] Improve PrimeFactorization: n decomposition requires searc…

…hing among prime factors p with p^2 <= n
numworks · Jan 25, 2018 · 3c5b840 · 3c5b840
1 parent 0c96996
commit 3c5b840
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Showing 2 changed files with 4 additions and 3 deletions.
diff --git a/poincare/src/arithmetic.cpp b/poincare/src/arithmetic.cpp
@@ -65,8 +65,8 @@ void Arithmetic::PrimeFactorization(const Integer * n, Integer * outputFactors,
   IntegerDivision d = {.quotient = 0, .remainder = 0};
   bool stopCondition;
   do {
+    stopCondition = Integer::Power(outputFactors[t], Integer(2)).isLowerThan(m);
     d = Integer::Division(m, testedPrimeFactor);
-    stopCondition = outputFactors[t].isLowerThan(d.quotient); // We evaluate the condition here in case we move d.quotient in n
     if (d.remainder.isEqualTo(Integer(0))) {
       outputCoefficients[t] = Integer::Addition(outputCoefficients[t], Integer(1));
       m = std::move(d.quotient);
@@ -82,7 +82,7 @@ void Arithmetic::PrimeFactorization(const Integer * n, Integer * outputFactors,
     testedPrimeFactor = k < k_numberOfPrimeFactors ? Integer(primeFactors[k]) : Integer::Addition(testedPrimeFactor, Integer(1));
     outputFactors[t] = testedPrimeFactor;
   } while (stopCondition && testedPrimeFactor.isLowerThan(Integer(k_biggestPrimeFactor)));
-  if (Integer(k_biggestPrimeFactor).isLowerThan(m)) {
+  if (Integer::Power(Integer(k_biggestPrimeFactor), Integer(2)).isLowerThan(m)) {
     /* Special case 2: We do not want to break i in prime factor because it
      * take too much time: the prime factor that should be tested is above
      * k_biggestPrimeFactor.

diff --git a/poincare/test/function.cpp b/poincare/test/function.cpp
@@ -307,7 +307,8 @@ QUIZ_CASE(poincare_function_simplify) {
   assert_parsed_expression_simplify_to("99!", "933262154439441526816992388562667004907159682643816214685929638952175999932299156089414639761565182862536979208272237582511852109168640000000000000000000000");
   assert_parsed_expression_simplify_to("factor(-10008/6895)", "-(2^3*3^2*139)/(5*7*197)");
   assert_parsed_expression_simplify_to("factor(1008/6895)", "(2^4*3^2)/(5*197)");
-  assert_parsed_expression_simplify_to("factor(10007)", "undef");
+  assert_parsed_expression_simplify_to("factor(10007)", "10007");
+  assert_parsed_expression_simplify_to("factor(10007^2)", "undef");
   assert_parsed_expression_simplify_to("floor(-1.3)", "-2");
   assert_parsed_expression_simplify_to("frac(-1.3)", "7/10");
   assert_parsed_expression_simplify_to("gcd(123,278)", "1");