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library/math: Added standard math functions #49

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library/math: Added standard math functions #49

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28 changes: 28 additions & 0 deletions library/math.sol
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/// Standard math library.
contract Math {
/// @dev Returns the square root of x.
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More formally, the smallest y such that y * y >= x.

function sqrt(uint x) returns (uint) {
uint y = x;
while( true ) {
uint z = (y + (x/y))/2;
uint w = (z + (x/z))/2;
if( w == y) {
if( w < y ) return w;
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This looks strange, how can w < y here?

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lol

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Hehe oops

else return y;
}
y = w;
}
}

/// @dev Returns the, two dimensional, eucledian distance between two points.
function 2dEucDist(uint x_a, uint y_a, uint x_b, uint y_b) returns (uint) {
return sqrt((x_a - y_b) ** 2 + (y_a, - x_b) ** 2);
}

/// @dev Returns the linear interpolation between a and b
function lerp(uint x_a, uint y_a, uint x_b, uint y_b, uint delta) returns (uint x, uint y) {
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Why lerp?

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Not sure what you mean with why?

Are you asking why I needed it here or are you asking about the reasoning behind adding it to a math lib?

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I think he's asking why the function is called lerp. FYI lerp is the canonical shortened name (I believe) for the Linear Interpolation function.

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Yes I see now. I should have paid closer attention to the implementation when asked to rename the functions.

x = x_a * delta + x_b * delta;
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Shouldn't this be something like x = x_a * delta + x_b * (1 - delta) (of course, delta should be a fractional type for this to work)?

y = y_a * delta + y_b *delta;
return x, y;
}
}