Real-World Examples
Parabolas, saddles, and contours in everyday objects
3D Surfaces
Functions with two inputs and their geometry
πΊοΈ Google Maps Knows Your Elevation
You're at latitude 28.6139, longitude 77.2090 (Delhi). Google Maps shows: elevation 216 meters.
How? Every (latitude, longitude) pair maps to exactly one elevation value. That's a function with two inputs producing one output:
Now rotate the 3D surface above. Every point on the floor has a height . Collect all these heights and you get the surface.
This is multivariable calculus β understanding functions where multiple inputs affect the output.
Apply the Concepts
Test your understanding of multivariable functions
For function , the gradient is at your current position. In which direction should you move to increase most rapidly?



