DragginMath: Flick Up/Down to Fold/Unfold

An operator tree shows all the relationships between an equation’s parts. But sometimes a full tree expansion has more detail than you want. Or perhaps you need to be persuaded that a tree really does represent the equation you entered.

Flick up on any operator to fold its subtree into a straight sequence of symbols just like what you see in the Top Text. Flick down anywhere on the sequence to unfold it back into a tree. Watch the animation and notice that no symbols cross over each other or change into other symbols when folding or unfolding: they only move up and down. The only difference in symbols is the injection of parentheses when folding up, which a tree doesn’t need ever but a sequence does sometimes. Use this feature to hide the details of a tree, showing only the amount of structure needed to think about your next step in solving a problem.

For example, enter a*b+c*d+e*f. Flick up on each of the * nodes to only see the additive aspect of the tree structure. Flick up on the + nodes to see a single sequence of symbols. Flick down on the sequence of symbols to turn it into a tree again. Flick up on + at the root to go back to the single line of symbols. You have a lot of choices here: you can fold any operator’s subtree.

You can interact only with the root of a folded-up subtree. You cannot interact with other nodes in the sequence of symbols. Most interactions with a folded-up subtree cause it to automatically fold down again.

Folding/unfolding is not an algebraic action. It changes where DragginMath draws symbols on the screen, but never in any way that changes their meaning.

Flicks that fold/unfold are not remembered as steps in History ⬆️.