Entering Data

Data Entry

Enter or edit data in the Data Input Form — a spreadsheet-style table with editing tools, range fills, and simple formula support.

New data can be entered, or existing data modified, in Edit ▸ Edit Data, which opens the Data Input Form. You can type or paste data directly, fill σ columns automatically, generate ranges, or enter simple formulas such as =2*x+1.

01Data mode and project mode

CFTool operates in two modes: Data mode (the default at startup) and Project mode.

Data mode saves simple text files as columns of data. Whether you use Save Data or Save Data As, the data window always writes a text file to disk before returning you to the plot (unless you cancel or close the edit window). Save Data writes the data — prompting for a filename for new data, or updating the active file — then plots it. Save Data As writes to a new text file, leaving any existing file unchanged, and plots the new file.

Project mode is entered by saving the current graph with File ▸ Save Project, or by opening an existing project. Project files hold the raw data plus formatting, any fit, and other modifications; saving a project does not delete the original text file — both are kept. In project mode the Data Input Form modifies the project data: Save Data updates the project but does not write to disk (save the project from the File menu), while Save Data As creates a new text file, closes the project unchanged, and returns you to data mode.

02Opening the data sheet

Choose Edit ▸ Edit Data. The table appears with columns:

• X_Data
• Y_Data
• σY
• σX (only visible when X errors are enabled)

03Entering and editing values

• Type directly into any cell.
• Double-click to edit an existing value.
• Press Enter/Return to confirm and move down one row.
• Move horizontally with Tab or Shift+Tab.

04Using formulas

Any cell can begin with = to indicate a formula — for example =2*x+1, =sin(x), =sqrt(y). Formulas can reference column names (x, y, sy, sx) and use standard functions (sin, cos, tan, exp, log, log10, sqrt, …). CFTool evaluates the formula automatically using values from the reference column.

Fill down: to copy a formula to lower cells, select the source cell plus the cells to update (or the whole column) and use Ctrl+D (Cmd+D on macOS), or right-click → Fill Down. You can freely mix typed numbers and formulas.

05Copying and pasting blocks

You can paste directly from Excel®, LibreOffice, or any tab/comma-separated text:

• Select the top-left cell where the pasted block should start.
• Press Ctrl+V / Cmd+V, or right-click → Paste Selection. The block replaces cells below and to the right of the anchor.
• Pasted data can be one to four columns; extra columns are ignored.

To copy, select a region or column header and press Ctrl+C / Cmd+C, or right-click → Copy.

06Table context menu

Right-click the table for quick actions:

• Paste Selection — paste from the clipboard starting at the selected cell.
• Copy Selection — copy highlighted cells.
• Clear Selection — erase selected cells.
• Fill Down — copy the top cell down the selected area (or full column).
• Recalculate — re-evaluate formulas when a source column has changed.
• Edit formula — edit a cell’s formula after evaluation.
• Convert data — convert a column to its decimal or natural logarithm, or reverse the conversion.

07Auto-fill tools (right-hand panel)

• Auto Fill Sigma — fill the x- or y-sigma column with a constant value (from the n box), with n × the corresponding x or y value, or with the square root of the corresponding value. Select any cell in the target column to choose it (only needed in four-column mode). A formula also works.
• Auto Fill Range — fill a column with a numerical sequence: select the top cell, set Start, End and Step, then Apply. Use a negative step for descending sequences.
• Swap x and y data — swaps the values in the two columns.

08Managing rows and saving

Buttons below the table:

• Add Row — append a blank line to the bottom.
• Insert Row — insert a blank line above the selected row.
• Delete Row — remove the selected line.

Save Data saves the current sheet as a text file (or returns data to a project); Save Data As writes to a new text file under a new name, leaving any previously saved file unchanged.

09Keyboard shortcuts

10Tips

• Formula columns can be updated (Recalculate) if you change the values they depend on.
• The paste anchor position matters — pastes always start at the active top-left cell.
• To discard changes, close the window with the ✕ rather than saving.