Questions tagged [math]
The math tag has no usage guidance.
11
questions
0
votes
0answers
26 views
Division and floor rounding with 18 decimals
I am recreating a UNISWAP-like AMM and have encountered problems anytime I want to divide the balances of tokens in my pool. For example: I want to require() that tokens are deposited in the correct ...
1
vote
0answers
14 views
Calculate exponential growth using decimals
Is there any way to calculate the following in Solidity?
468750 * 2.718281828459045 ** (x * 0.003662040962) - 468750
Typically I would convert the decimals using decimal * 10 ** 18 but with the ...
0
votes
0answers
17 views
How to get the square root of a big number as returned by web3.utils.toBN()?
I'm working with big numbers as returned by web3.utils.toBN(). According to the web3 documentation, this function returns a BN.js instance. However, there doesn't seem to be a square root function on ...
0
votes
0answers
21 views
Can't store the value of a math operation. It's always 0
contract MyContract {
uint public priceUSD = 1.70 * 10**8; // USD
uint public priceEth;
.........
function setPrice(uint newPriceUSD) external ownerOnly() returns(uint, uint) {
uint ...
0
votes
0answers
16 views
Calculating price: “Operator / not compatible”
function getLatestPrice() public view returns (int, uint8) {
(
uint80 roundID,
int price,
uint startedAt,
uint timeStamp,
uint80 answeredInRound
) = priceFeed....
0
votes
1answer
33 views
How can you cheaply choose from a dynamic array randomly, with an oracle generated seed number, in Solidity?
In JS you could use this and call it a day.
let randomArrayEntry = myArray[Math.floor(Math.random() * myArray.length)];
However, in Solidity everything is deterministic unless you call an outside ...
0
votes
1answer
29 views
Why DS-Math add WAD/2 or RAY/2 in WAD,RAY multiply function
//rounds to zero if x*y < WAD / 2
function wmul(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, y), WAD / 2) / WAD;
}
//rounds to zero if x*y < WAD / 2
function rmul(uint x, ...
0
votes
0answers
21 views
calculate exchange rate of WBTC TO WETH in big numbers
i want to calculate how much WETH i will get for a given WBTC amount:
const amountsEth =
kyber
.methods
.getExpectedRate(
addresses.tokens.wbtc,
'...
1
vote
1answer
39 views
How can I use decimal in solidity
how can i calculate:
1083.83 / 8.25 = 131.37.
As I see its not possible in simple way. I have tried a lot of math function but not works.
Is there any solution for this?
4
votes
0answers
28 views
How can i do 2^0.3 (exponent below 1) using integers?
simple problem, but i can't seem to wrap my head around it in solidity.
how can i do 2^0.3 (exponent smaller then 1) in solidity using integers.
thanks in advance
K.
1
vote
1answer
40 views
Why don't decimals work in solidity?
I've read this question and answer thread about representing decimal values in solidity, and I understand that math is entirely done using fixed-point.
However, I'm curious as to why this is the case. ...
