Вычисление разностей

The Residuals command computes the vertical difference between data points and a gridded surface or a USGS DEM file. A residual is the difference between the Z value of a point in a data file and the interpolated Z value at the same (X,Y) location on a gridded surface. The Residual command can give you a quantitative measure of the agreement between a grid file and the original data, or can be used to determine the Z value at any (X,Y) location from the grid file.

The formula used to compute a residual value is:

Zres = Zdat - Zgrd

where:

Zres is the residual value

Zdat is the Z value in the data file

Zgrd is the Z value of the surface at the X,Y coordinate of the point from the data file.

If the Z value in the data file is greater than the Z value derived from the gridded surface, the residual value is positive. For example, if the residual is 4.5, the data file Z value is 4.5 units above the gridded surface.

The results of the Residual command are written to a Worksheet window, and can be saved as a data file from the worksheet. When you perform the residuals operation, a Worksheet window is automatically opened and the data file is written to the worksheet along with the newly generated residual information. The Worksheet window uses the name of the data file. This allows you to easily save the residual information in the existing data file, or allows you to save the data and residuals in a new data file.

If you want to obtain statistical information on the calculated residuals, you can use the Statistics command from the Worksheet Compute menu.

The Grid Residuals Dialog Box

When you choose the Residuals command from the Grid menu, you must specify the grid file or USGS DEM file and the data file to be compared, and the Grid Residuals dialog box is displayed.

* The Data Columns group allows you to specify the columns where your X, Y and Z data reside in the data file. Select the appropriate columns from the drop-down list boxes.

* The Store residuals in column edit box allows you to specify the column to contain the residuals values. When you perform the residuals calculation, a Worksheet window is automatically opened, and the data file and the residual data are placed in the worksheet. By default Surfer selects the first column to the right that does not contain any data from the data file.

Вычисление соответствия между вычисленным файлом сетки и первоначальным файлом данных.

После использования команды Residuals:

1. В рабочем листе выделите колонку левее

Compute Statistics

The Statistics command calculates statistical values for a group of selected numeric cells. The selected cells can be any combination of cells, rows or columns. The statistics include:

the total number of numeric cells.

the sum of the values in the selected cells.

the average of the values in the selected cells.

the standard deviation for the selected cells.

the minimum value in the group of selected cells.

the maximum value in the group of selected cells.

Any non-numeric cells in the selected range are ignored. The calculated results can be copied to the Clipboard and pasted to the worksheet.

The Statistics Dialog Box

To calculate the statistics for any combination of cells, rows or columns, first select the cells on which the statistical functions are to be performed. When you choose the Statistics command from the Compute menu the Statistics dialog box appears.

The Results group box displays the calculated values for the selected cells. The checkboxes specify the statistical values to be copied to the Clipboard.

The Copy labels to Clipboard checkbox makes a copy of the labels for each of the statistical values that are copied to the Clipboard.

When you want to paste the results into the worksheet, highlight the top left cell for the block of cells to receive statistical results (and the labels if also copied). If data exists in the selected column or the next column to the right, that data might be overwritten with the statistical results. Choose the Paste command from the Worksheet Edit menu (or press SHIFT+INS or CTRL+V) to paste the values into the worksheet.