Mathematically modeling a real system in C#

[sysprog]

Two other options for graphing:

This one is really a downloadable emulator; not an online calculator $=$
https://www.tinspireapps.com/Online-Calculators/TI83-Online-Calculator.php

GeoGebra, available at https://geogebra.org, can be used online, and can be downloaded for offline use, including a downloadable graphing calculator.

 

[Mark44]

I have been trying... but the graphing calculator does not let me... it is very frustrating, I am only using it because it comes with my computer .

It looks like you are using the Windows Calculator to do the graphs.
Click the icon circled below to open the Graph Options dialog.

On the Graph Options dialog, you can change the scale on the x-axis or the y-axis, change the units (radians, degrees, or grads), or change the line thickness.

You'll get a more useful graph by changing the limits on the y-axis to better show the oscillation.