Stupid math.

1,298

Author

May 31, 2005 08:13 PM

Google: (-.5)^(1/3)= Output: -.5^(1 / 3) = -0.793700526 Mathomatic: (-.5)^(1/3) Output: answer = -0.793700525984 Maxima: bfloat((-.5)^(1/3)) Output: -7.93700525984099737375852819636154130195746663949926504904142880912608252812109586636772106631[...]B-1 C++: std::pow(-0.5, 1.0/3.0) Output: nan It would appear that 3 other sources are calling C++ a dirty liar.

Chess is played by three people. Two people play the game; the third provides moral support for the pawns. The object of the game is to kill your opponent by flinging captured pieces at his head. Since the only piece that can be killed is a pawn, the two armies agree to meet in a pawn-infested area (or even a pawn shop) and kill as many pawns as possible in the crossfire. If the game goes on for an hour, one player may legally attempt to gouge out the other player's eyes with his King.

ricekrispyw

388

May 31, 2005 08:24 PM

Wierd.

I think it's a conspiracy.

[smile]

The best way to predict the future is to invent it.

Polymorphic OOP

954

May 31, 2005 08:29 PM

The built-in floating point C and C++ pows aren't meant to handle negative bases. They are described as

exp( power * log( base ) )

smart_idiot

1,298

Author

May 31, 2005 08:29 PM

The problem is that there is 3 possible solutions; one is real and two are imaginary. C++ is using one of the imaginary solutions.

std::pow(std::complex<double>(-0.5), std::complex<double>(1.0/3.0)) gives me 0.39685+0.687365i.

I wanted the real one, that seemed like the obvious one to pick.

Chess is played by three people. Two people play the game; the third provides moral support for the pawns. The object of the game is to kill your opponent by flinging captured pieces at his head. Since the only piece that can be killed is a pawn, the two armies agree to meet in a pawn-infested area (or even a pawn shop) and kill as many pawns as possible in the crossfire. If the game goes on for an hour, one player may legally attempt to gouge out the other player's eyes with his King.

smart_idiot

1,298

Author

May 31, 2005 08:47 PM

I guess the best solution would be to check if the base is negative, and if it is use -((-base)^(1/3)) instead, which seems to give the (or one of the) right answer(s).

Chess is played by three people. Two people play the game; the third provides moral support for the pawns. The object of the game is to kill your opponent by flinging captured pieces at his head. Since the only piece that can be killed is a pawn, the two armies agree to meet in a pawn-infested area (or even a pawn shop) and kill as many pawns as possible in the crossfire. If the game goes on for an hour, one player may legally attempt to gouge out the other player's eyes with his King.

Stupid math.

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Stupid math.

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