XL2000: Faulty Zero Value When You Fill Linear Trend Series (214366)

SYMPTOMS

When you fill a linear trend series in a worksheet in Microsoft Excel, the series may contain a value similar to either of the following:

    2.84217E-14

-or-

   -1.70530E-13

One of these values appears where you expect to see a zero value. For example, if you expect the linear trend series to appear as follows

   100   75   50   25   0             -25   -50

it appears as follows:

   100   75   50   25   2.84217E-14   -25   -50

CAUSE

This problem may occur if both of the following conditions are true:

The linear trend series should contain the value zero (0).

-and-
You are using the right mouse button to create the linear trend series.

Specifically, this problem results from a rounding error that occurs in Microsoft Excel when you work with near-zero values.

WORKAROUND

To work around this problem, clear the cell that contains the incorrect value and type a zero (0) in the cell.

To prevent this problem from occurring, follow these steps:

Select all the cells to be used by the series.
On the Edit menu, click Fill, and then click Series.

The problem does not occur when you use this method to fill a linear trend series.

MORE INFORMATION

Example of the Problem

In Microsoft Excel, you can create a linear trend series in which each value is separated from the next value in the series by a set amount. To do this and see an example of the problem, follow these steps:

Type the values that you want to use to establish the series. For example:
```
      A1: 100
      A2: 75
					
```
Select the cells. Right-click the fill handle at the lower-right corner of cell A2. Drag the fill handle down to cell A9, and then release the mouse button.
On the shortcut menu, click Linear Trend.

You should see the following values:

   A1: 100
   A2: 75
   A3: 50
   A4: 25
   A5: 2.84217E-14
   A6: -25
   A7: -50
   A8: -75
   A9: -100

Each value in the series is 25 less than the preceding value.

Note that the value in cell A5 is incorrect. Although it is very close to zero (0.0000000000000284217), it is not actually zero.

REFERENCES

For additional information about rounding errors, click the article number below to view the article in the Microsoft Knowledge Base:

182196 XL2000: Floating-Point Arithmetic May Give Inaccurate Results