R：Quantstrat如何进行交易以实现投资组合的完全权益？

I'm still playing around with Guy Yollins quantstrat example. In this example he buys 1000 shares of the SPY when it crosses its 10 day MA. Since we define an initial equity, is it possible to always buy for the whole portfolio amount and not just 900 shares? 'all' didn't work for the enter, just the exit..I'm still playing around with Guy Yollins quant