Replace Number division algorithm

* Replace division with faster algorithm.
* Correct some rounding bugs in multiplication.
* Add tests for rounding bugs.
This commit is contained in:
Howard Hinnant
2022-12-22 12:20:56 -05:00
committed by Elliot Lee
parent e354497f63
commit 6eaaa7bcfa
2 changed files with 175 additions and 50 deletions

View File

@@ -150,25 +150,94 @@ public:
{
testcase("test_mul");
using Case = std::tuple<Number, Number, Number>;
Case c[]{
{Number{7}, Number{8}, Number{56}},
{Number{1414213562373095, -15},
Number{1414213562373095, -15},
Number{2000000000000000, -15}},
{Number{-1414213562373095, -15},
Number{1414213562373095, -15},
Number{-2000000000000000, -15}},
{Number{-1414213562373095, -15},
Number{-1414213562373095, -15},
Number{2000000000000000, -15}},
{Number{3214285714285706, -15},
Number{3111111111111119, -15},
Number{1000000000000000, -14}},
{Number{1000000000000000, -32768},
Number{1000000000000000, -32768},
Number{0}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x * y == z);
saveNumberRoundMode save{Number::setround(Number::to_nearest)};
{
Case c[]{
{Number{7}, Number{8}, Number{56}},
{Number{1414213562373095, -15},
Number{1414213562373095, -15},
Number{2000000000000000, -15}},
{Number{-1414213562373095, -15},
Number{1414213562373095, -15},
Number{-2000000000000000, -15}},
{Number{-1414213562373095, -15},
Number{-1414213562373095, -15},
Number{2000000000000000, -15}},
{Number{3214285714285706, -15},
Number{3111111111111119, -15},
Number{1000000000000000, -14}},
{Number{1000000000000000, -32768},
Number{1000000000000000, -32768},
Number{0}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x * y == z);
}
Number::setround(Number::towards_zero);
{
Case c[]{
{Number{7}, Number{8}, Number{56}},
{Number{1414213562373095, -15},
Number{1414213562373095, -15},
Number{1999999999999999, -15}},
{Number{-1414213562373095, -15},
Number{1414213562373095, -15},
Number{-1999999999999999, -15}},
{Number{-1414213562373095, -15},
Number{-1414213562373095, -15},
Number{1999999999999999, -15}},
{Number{3214285714285706, -15},
Number{3111111111111119, -15},
Number{9999999999999999, -15}},
{Number{1000000000000000, -32768},
Number{1000000000000000, -32768},
Number{0}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x * y == z);
}
Number::setround(Number::downward);
{
Case c[]{
{Number{7}, Number{8}, Number{56}},
{Number{1414213562373095, -15},
Number{1414213562373095, -15},
Number{1999999999999999, -15}},
{Number{-1414213562373095, -15},
Number{1414213562373095, -15},
Number{-2000000000000000, -15}},
{Number{-1414213562373095, -15},
Number{-1414213562373095, -15},
Number{1999999999999999, -15}},
{Number{3214285714285706, -15},
Number{3111111111111119, -15},
Number{9999999999999999, -15}},
{Number{1000000000000000, -32768},
Number{1000000000000000, -32768},
Number{0}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x * y == z);
}
Number::setround(Number::upward);
{
Case c[]{
{Number{7}, Number{8}, Number{56}},
{Number{1414213562373095, -15},
Number{1414213562373095, -15},
Number{2000000000000000, -15}},
{Number{-1414213562373095, -15},
Number{1414213562373095, -15},
Number{-1999999999999999, -15}},
{Number{-1414213562373095, -15},
Number{-1414213562373095, -15},
Number{2000000000000000, -15}},
{Number{3214285714285706, -15},
Number{3111111111111119, -15},
Number{1000000000000000, -14}},
{Number{1000000000000000, -32768},
Number{1000000000000000, -32768},
Number{0}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x * y == z);
}
bool caught = false;
try
{
@@ -187,13 +256,78 @@ public:
{
testcase("test_div");
using Case = std::tuple<Number, Number, Number>;
Case c[]{
{Number{1}, Number{2}, Number{5, -1}},
{Number{1}, Number{10}, Number{1, -1}},
{Number{1}, Number{-10}, Number{-1, -1}},
{Number{0}, Number{100}, Number{0}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x / y == z);
saveNumberRoundMode save{Number::setround(Number::to_nearest)};
{
Case c[]{
{Number{1}, Number{2}, Number{5, -1}},
{Number{1}, Number{10}, Number{1, -1}},
{Number{1}, Number{-10}, Number{-1, -1}},
{Number{0}, Number{100}, Number{0}},
{Number{1414213562373095, -10},
Number{1414213562373095, -10},
Number{1}},
{Number{9'999'999'999'999'999},
Number{1'000'000'000'000'000},
Number{9'999'999'999'999'999, -15}},
{Number{2}, Number{3}, Number{6'666'666'666'666'667, -16}},
{Number{-2}, Number{3}, Number{-6'666'666'666'666'667, -16}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x / y == z);
}
Number::setround(Number::towards_zero);
{
Case c[]{
{Number{1}, Number{2}, Number{5, -1}},
{Number{1}, Number{10}, Number{1, -1}},
{Number{1}, Number{-10}, Number{-1, -1}},
{Number{0}, Number{100}, Number{0}},
{Number{1414213562373095, -10},
Number{1414213562373095, -10},
Number{1}},
{Number{9'999'999'999'999'999},
Number{1'000'000'000'000'000},
Number{9'999'999'999'999'999, -15}},
{Number{2}, Number{3}, Number{6'666'666'666'666'666, -16}},
{Number{-2}, Number{3}, Number{-6'666'666'666'666'666, -16}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x / y == z);
}
Number::setround(Number::downward);
{
Case c[]{
{Number{1}, Number{2}, Number{5, -1}},
{Number{1}, Number{10}, Number{1, -1}},
{Number{1}, Number{-10}, Number{-1, -1}},
{Number{0}, Number{100}, Number{0}},
{Number{1414213562373095, -10},
Number{1414213562373095, -10},
Number{1}},
{Number{9'999'999'999'999'999},
Number{1'000'000'000'000'000},
Number{9'999'999'999'999'999, -15}},
{Number{2}, Number{3}, Number{6'666'666'666'666'666, -16}},
{Number{-2}, Number{3}, Number{-6'666'666'666'666'667, -16}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x / y == z);
}
Number::setround(Number::upward);
{
Case c[]{
{Number{1}, Number{2}, Number{5, -1}},
{Number{1}, Number{10}, Number{1, -1}},
{Number{1}, Number{-10}, Number{-1, -1}},
{Number{0}, Number{100}, Number{0}},
{Number{1414213562373095, -10},
Number{1414213562373095, -10},
Number{1}},
{Number{9'999'999'999'999'999},
Number{1'000'000'000'000'000},
Number{9'999'999'999'999'999, -15}},
{Number{2}, Number{3}, Number{6'666'666'666'666'667, -16}},
{Number{-2}, Number{3}, Number{-6'666'666'666'666'666, -16}}};
for (auto const& [x, y, z] : c)
BEAST_EXPECT(x / y == z);
}
bool caught = false;
try
{