faheel/BigInt

a bug in DIV

yunyng opened this issue · 1 comments

yunyng commented

Details

a bug in (1453302010683093905187502545111768308832134376934/(-10531))
the result is -1380022880000293790256148755589380714920912959
but the right is -138002280000293790256148755589380714920912959

in function "std::tuple<BigInt, BigInt> divide(const BigInt& dividend, const BigInt& divisor) "
"while (temp < dividend) " may change to "while (temp <= dividend) "

System info

  • OS: Red Hat 4.8.5-4
  • Compiler: gcc version 4.8.5
faheel commented

Withot changing the code for divide I added the following to the "Division of big numbers" test case in test/operators/binary_arithmetic.cpp and ran make test and got the expected result:

num1 = "1453302010683093905187502545111768308832134376934";
num2 = -10531;
REQUIRE(num1 / num2 == "-138002280000293790256148755589380714920912959");
Test project /home/faheel/Projects/Personal/BigInt/build
      Start  1: ConstructorsTest
 1/11 Test  #1: ConstructorsTest ....................   Passed    0.00 sec
      Start  2: FunctionsConversionTest
 2/11 Test  #2: FunctionsConversionTest .............   Passed    0.00 sec
      Start  3: FunctionsMathTest
 3/11 Test  #3: FunctionsMathTest ...................   Passed    0.60 sec
      Start  4: FunctionsRandomTest
 4/11 Test  #4: FunctionsRandomTest .................   Passed    0.07 sec
      Start  5: OperatorsArithmeticAssignmentTest
 5/11 Test  #5: OperatorsArithmeticAssignmentTest ...   Passed    0.01 sec
      Start  6: OperatorsAssignmentTest
 6/11 Test  #6: OperatorsAssignmentTest .............   Passed    0.00 sec
      Start  7: OperatorsBinaryArithmeticTest
 7/11 Test  #7: OperatorsBinaryArithmeticTest .......   Passed    0.14 sec
      Start  8: OperatorsIncrementDecrementTest
 8/11 Test  #8: OperatorsIncrementDecrementTest .....   Passed    0.00 sec
      Start  9: OperatorsIOStreamTest
 9/11 Test  #9: OperatorsIOStreamTest ...............   Passed    0.00 sec
      Start 10: OperatorsRelationalTest
10/11 Test #10: OperatorsRelationalTest .............   Passed    0.00 sec
      Start 11: OperatorsUnaryArithmeticTest
11/11 Test #11: OperatorsUnaryArithmeticTest ........   Passed    0.00 sec

100% tests passed, 0 tests failed out of 11

Total Test time (real) =   0.86 sec

Can you try the same and see whether the tests pass? Also, can you check whether you really got the wrong result that you mentioned (-1380022880000293790256148755589380714920912959)?