Fix ERR:NO SIGN CHNG or ERR:BOUND

Press these keys

Walkthrough

1. 1
   Inspect visually

   Graph the function and confirm a root or target point actually lies between the selected bounds.

2. 2
   Reorder bounds

   Left/lower must be less than right/upper, and the guess must lie inside.

3. 3
   Tighten one event

   Bracket a single crossing or turning point. A touching root may not create a sign change.

Worked example