it might be better

src/backtester.rs

@@ -199,12 +199,12 @@ impl Backtester {
         let shares =
             self.strategy
                 .calculate_position_size(price, portfolio_value, available_cash, signal);
-        if shares == 0 {
+        if shares <= 0.0 {
             return false;
         }
 
         let fill_price = Self::apply_slippage(price, "buy");
-        let cost = shares as f64 * fill_price;
+        let cost = shares * fill_price;
         if cost > self.cash {
             return false;
         }
@@ -214,7 +214,7 @@ impl Backtester {
             symbol.to_string(),
             BacktestPosition {
                 symbol: symbol.to_string(),
-                shares: shares as f64,
+                shares: shares,
                 entry_price: fill_price,
                 entry_time: timestamp,
                 entry_atr: signal.atr,
@@ -229,7 +229,7 @@ impl Backtester {
         self.trades.push(Trade {
             symbol: symbol.to_string(),
             side: "BUY".to_string(),
-            shares: shares as f64,
+            shares: shares,
             price: fill_price,
             timestamp,
             pnl: 0.0,