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# Technical Studies Reference

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### Study Subgraphs Subtract/Difference

This study calculates and displays the *Difference* of two study Subgraphs.

The study Subgraphs can be part of different studies on the chart, including the Add Additional Symbol study, or any of the main price graph Subgraphs. So it is possible to calculate the difference between the main price graph and the **Add Additional Symbol** study.

Let \(X^{(1)}\) and \(X^{(2)}\) be random variables respectively denoting the **Input Study 1** and **Input Study 2** Inputs, and let \(X^{(1)}_t\) and \(X^{(2)}_t\) be their respective values at Index \(t\). Let the Input **Study 2 Subgraph Offset** be denoted as \(k\).

If \(k = 0\), then the displayed value of **Study Subgraphs Subtract** at Index \(t\) is given by \(X^{(1)}_t - X^{(2)}_t\). If \(k \neq 0\), then the displayed value of **Study Subgraphs Subtract** is given by \(X^{(1)}_t - X^{(2)}_0\) for \(t \leq k\), and \(X^{(1)}_t - X^{(2)}_{t - k}\) for \(t > k\).

If the **Draw Zeros** Input is set to No, then **Study Subgraphs Subtract** is not drawn at Index \(t\) if its value is zero. Otherwise, it is drawn at Index \(t\) even if its value is zero.

If the **Perform Subtract With Zero Values** Input is set to No, then the value of **Study Subgraphs Subtract** is replaced with \(0\) at Index \(t\) if either term in the difference is zero. Otherwise, the two terms are subtracted even if either of them is zero.

#### Inputs

**Input Study 1**: Use this Input to select the study and study Subgraph for Study Subgraph 1 used in the difference calculation.**Input Study 2**: Use this Input to select the study and study Subgraph for Study Subgraph 2 used in the difference calculation.**Study 2 Subgraph Offset**: This Input specifies the offset, in chart bars, from the current bar being calculated when determining the value for Study Subgraph 2. It needs to be entered as a positive value and it specifies the number of bars back from the current bar being calculated, when obtaining the value from the Study 2 Subgraph selected with the**Input Study 2**Input.**Draw Zeros**: When this Input is set to Yes, then zero values from the study Subgraph will be drawn. Otherwise, they will not be.**Perform Subtract With Zero Values**: When this input is set to Yes, the default, then**Input Study 1**and**Input Study 2**of the**Based On**studies are always subtracted. When this is set to No, then at chart columns where the either**Input Study 1**or**Input Study 2**from the**Based On**studies is 0, then the subtraction does not occur and a zero value is used instead.

*Last modified Wednesday, 15th January, 2020.