Function simple_returns 

pub fn simple_returns(prices: &[f64]) -> FinanceResult<Vec<f64>>

Simple returns for consecutive prices: length prices.len() - 1.

Examples

use finance_solution::{simple_returns, FinanceError};

assert_eq!(simple_returns(&[100.0, 110.0]).unwrap().len(), 1);
match simple_returns(&[100.0]) {
    Err(FinanceError::Unsolvable { message }) => assert!(message.contains("two")),
    other => panic!("expected Unsolvable, got {other:?}"),
}