Interactive assignments

An interactive assignment is the following command:

• x [ = ] interactive(y, z, [ x', x'',] str, f)

With eukleides, variable x is simply set to y. With xeukleides, it allows, while viewing, to modify the value of the numerical variable x using the arrow keys. The initial value of x is y, the increment is z. The optional parameters x' and x" are the lower and upper bounds of x. The string str has to contain one uppercase letter. To modify x, one has to press first the corresponding key (at the beginning, the default state is A). The permitted values of f are right (in this case, x will be incremented by pressing the right arrow key and decremented by pressing the left arrow key) or up (in this case, x will be incremented by pressing the up arrow key and decremented by pressing the down arrow key).

When the equal symbol is not present, one may capture the actual value of variable x. In this case, parameter y has to be a simple number (not an expression). When pressing the F1 key, the initial value in the source code is replaced by the actual value and the program switches to editing mode.