Fix scaling bug in calculate_implied_rate sdk method

[DannyDelott]

Getting strange output for calculate_implied_rate.. 1255.82% seems really high! 😛

Reproduction

Using this:

hyperdrive/crates/hyperdrive-math/src/short/open.rs

Lines 160 to 165 in 1576e4c

	pub fn calculate_implied_rate(
	&self,
	bond_amount: FixedPoint,
	open_vault_share_price: FixedPoint,
	variable_apy: FixedPoint,
	) -> Result<I256> {

I'm calling it with these args:

bond_amount: 1000000000000000000 // "1"
open_vault_share_price: 1005446844189634821 // "1.005446844189634821"
variable_apy: 130000000000000000 // "0.13"

We get back: 12563492079684959896 // "12.563492079684959896"

Formatted and rendered in the ui under Implied Variable Rate:

Solution

We just need to adjust the variable rate here (since this term is shorter than a year):

hyperdrive/crates/hyperdrive-math/src/short/open.rs

Line 167 in 1576e4c

let base_proceeds = bond_amount * variable_apy;

.

Reference

https://discord.com/channels/754739461707006013/1224785900073128080/1233120393938604142