我有以下代码（vue 3）：

const salesTotal = computed(() => {
      let totalSalesAmount = new Array(numberOfPeriods).fill(0);
      return totalSalesAmount;
    });

    const cogsTotal = computed(() => {
      let totalCOGSAmount = new Array(numberOfPeriods).fill(0);
      return totalCOGSAmount;
    });

    const grossMarginTotal = computed(() => {
      let grossMarginAmount = [];
      for (let k = 0; k < numberOfPeriods; k++) {
        grossMarginAmount[k] = salesTotal[k] + cogsTotal[k];
      }
      return grossMarginAmount;
    });

numberOfPeriods是5。当我打印salesTotal和cogsTotal时，我得到的是[ 0, 0, 0, 0, 0 ]，但是[ null, null, null, null, null ]得到的是grossMarginTotal。我做错了什么？