Precision

->scale() (or the scale config key) sets the decimal places of every amount: P&L, volume, value, commission, their averages, the expectancy’s and risk/reward ratio’s average win and loss, and the drawdown. bcmath truncates rather than rounds, so each figure is truncated to its scale as it is stored; ratios are divided at a higher working scale first, so an operand below the result’s precision — a loss of 0.00005 BTC, a deviation of a few basis points — still counts. Ratios and percentages are reported at a fixed scale, whatever the run’s:

Each trade’s own numbers are exact: Trade::make(), fromArray() and fromRow() keep every amount at its own decimal places (at least 10), and its P&L and value at entry (size × open price) are computed without truncation, so the run’s scale truncates them only once, into its results. Building trades shows a high-precision example.