KSiag defaults to using "C" like expressions similar to those found in other spreadsheets. When you use a number as the first character of a cell, the cell is automatically assumed to be a C expression. Thus to do something like 1+2, just enter 1+2 and hit return. Other more complex expressions require the use of functions. For example, abs(), or absolute value.
The abs function starts with the letter "a", which as you learned in the previous lesson will cause the cell to be interpreted as a label. Not an expression like we want. You can tell this is happening with in-place cell editing because as soon as you type "a" the Cell Info box changes to "Label:". In order to force a cell to be identified as a C expression you must start the expression with an equals sign ( = ). This also is identical behavior to other spreadsheets. When you do this the Cell Info box changes to "C expression:" and you can then type the function in normally. The graphic below demonstrates this:
This is the equation toolbar before we type anything:
This is what happens when we type "=". Notice it does not show up in the
cell editor, but the Cell Info box changes to "C expression":
Now we just enter the expression and hit Enter:
Like the double quote ( " ) character for labels, the equals sign does not show up in the cell editor because it is not part of the expression. It is a command to KSiag saying that the following input is going to be an expression. This deviates (correctly) from some other spreadsheets.