Accessing indicator value from x bars ago

[BishopM05]

Hi, this is probably a basic question, but I'm having a hard time incorporating previous bars into the logic. Here's what I want to do: Draw an arrow when the MACD value of bar 0 ago is .01 greater than the MACD value of bar 1 ago.


if (MACD(12, 26, 9)[0] - MACD(12, 26, 9)[1] > 0.01)
{
DrawArrowDown("My down arrow" + CurrentBar, false, 0, High[0] + 4 * TickSize, Color.Red);
}

How can I reference the previous bars? It will compile, but the arrows will not plot. The arrow will plot if the bars ago are set to [0]...for example something like

if (MACD(12, 26, 9)[0] > 0.01)
{
DrawArrowDown("My down arrow" + CurrentBar, false, 0, High[0] + 4 * TickSize, Color.Red);
}

Thanks

[koganam]

Hi, this is probably a basic question, but I'm having a hard time incorporating previous bars into the logic. Here's what I want to do: Draw an arrow when the MACD value of bar 0 ago is .01 greater than the MACD value of bar 1 ago.


if (MACD(12, 26, 9)[0] - MACD(12, 26, 9)[1] > 0.01)
{
DrawArrowDown("My down arrow" + CurrentBar, false, 0, High[0] + 4 * TickSize, Color.Red);
}

How can I reference the previous bars? It will compile, but the arrows will not plot. The arrow will plot if the bars ago are set to [0]...for example something like

if (MACD(12, 26, 9)[0] > 0.01)
{
DrawArrowDown("My down arrow" + CurrentBar, false, 0, High[0] + 4 * TickSize, Color.Red);
}

Thanks

Any messages in the log?

[BishopM05]

Yes, I'm getting the not enough bars error. However, the chart is displaying more than 5 bars...

"Error on calling 'OnBarUpdate' method for indicator 'MACDMarker' on bar 0: You are accessing an index with a value that is invalid since its out of range. I.E. accessing a series [barsAgo] with a value of 5 when there are only 4 bars on the chart."

[VTtrader]

It doesn't matter how many bars are on the chart, OnBarUpdate() is called for every bar on the chart. Your formula references the previous bars MACD value, and on the first bar there is no previous bar.

So in OnBarUpdate() before your code include a check for enough bars:
if (CurrentBar < 1) return;

The number of bars to check for is not always the same, but for what you've posted 1 should be enough.

VT

[BishopM05]

Thanks for the explanation!