Rate Model

The rate model uses a smooth utilization polynomial. It is not a two-slope kinked model.

u = borrows / (liquidity + borrows)
annual_rate = c3 × (c1×u + c1×u^32 + c2×u^64)
rate_per_second = annual_rate / 31,556,952

All contract values are WAD-scaled. Defaults are c1 = 0.1, c2 = 0.3, c3 = 3.5; these are configurable, not immutable market rates. get_coefficients returns current values. The admin setter rejects coefficients whose implied 100%-utilization APR exceeds 1000%. Utilization is clamped to 100%, and inputs to the borrow-rate calculation are capped at 10^36. The constructor accepts a Registry argument for deployment compatibility but does not persist or use it. The model’s admin may change coefficients and upgrade WASM. See Math Reference for integer scaling and interest rounding.

Function signatures

These signatures are copied from the reviewed Rust implementation. env is supplied by Soroban and is not a transaction argument. Result errors and panics must be handled by the caller; simulation does not guarantee later execution. Public methods include privileged and internal-contract callbacks, not just user entrypoints.

__constructor

pub fn __constructor(env: &Env, admin: Address, _registry_contract: Address)

set_coefficients

pub fn set_coefficients(env: &Env, c1: u128, c2: u128, c3: u128)

get_coefficients

pub fn get_coefficients(env: &Env) -> (u128, u128, u128)

get_admin

pub fn get_admin(env: &Env) -> Address

upgrade

pub fn upgrade(env: &Env, new_wasm_hash: BytesN<32>)

get_borrow_rate_per_sec

pub fn get_borrow_rate_per_sec(
        env: &Env,
        liquidity_wad: U256,
        borrows_wad: U256,
    ) -> Result<U256, InterestRateError>

get_utilisation_ratio

pub fn get_utilisation_ratio(
        env: &Env,
        liquidity_wad: U256,
        borrows_wad: U256,
    ) -> Result<U256, InterestRateError>

Source reference

Protocol_V1_Soroban_testnet/contracts/RateModelContract/src/rate_model.rs

Introduction

Contract Reference

TypeScript Integration

Integration Guides

Function signatures

__constructor

set_coefficients

get_coefficients

get_admin

upgrade

get_borrow_rate_per_sec

get_utilisation_ratio

Source reference

​Function signatures

​__constructor

​set_coefficients

​get_coefficients

​get_admin

​upgrade

​get_borrow_rate_per_sec

​get_utilisation_ratio

​Source reference

Function signatures

__constructor

set_coefficients

get_coefficients

get_admin

upgrade

get_borrow_rate_per_sec

get_utilisation_ratio

Source reference