## 3D Printer Models for MAT 232

Posted in Computers, Math, Teaching and Learning by pgadey on 2019/11/07

This semester, I am teaching MAT 232 Multivariable Calculus. We often talk about level curves and use the saddle surface $z = x^2 - y^2$ as a key example. Every time it comes up, I ask students to stare at the part of their hand where the thumb meets the palm. Of course, they stare at me like I am crazy! This region of the hand is a good model for a saddle surface. If you start looking around at biological examples, you’ll see saddle surfaces everywhere.

I got interested in getting some 3D printed models of saddle surfaces to hand around the class. I found a great project 3D Printed Models for Multivariable Calculus put together by John Zweck. The STL files for the models are freely available, and I asked Reinhard Grassmann of the Continuum Robotics Lab if he could 3D print some models of saddle surfaces and the paraboloid $z = x^2 + y^2$ for me.

They arrived yesterday and they turned out GREAT! You can clearly see the level curves in one model, and the coordinate grid in another. They feel great to hold and are durable enough to hand around to a class of students.

Tagged with: , ,

## Backing Up with TAR

Posted in Computers by pgadey on 2019/11/03

My laptop is on its last legs. I manage to wear out laptops at an alarming rate. The Lenovo X220 has served me well, but the battery is flaking out and it shuts down everytime the wind blows. So, I looked up some options for backing up the disk. I found this brief guide to backing up.

Here are the relevant commands for reference:

```\$ sudo tar -cvpzf backup.tar.gz --exclude=/backup.tar.gz --one-file-system / \$ sudo tar -xvpzf /path/to/backup.tar.gz -C /restore/location --numeric-owner```

Tagged with: , ,

## Symmetry @ Otterbein

Posted in Computers by pgadey on 2019/06/03

The image represents a molecule of chloropentacarbonylmanganese or ClMn(CO)5. For the last half-hour or so, I have been playing around in the Symmetry Gallery put together by Otterbein. Lots of lovely molecules with high degrees of symmetry. It is remarkable (to me) that such things even exist in nature. I encourage you to go and check out the lovely interactive demos on the site.

## Office Camera

Posted in Computers by pgadey on 2016/09/13

There is a camera in my office which I use to take photos of the white board. The photos are automatically posted to http://pgadey.ca/office/cam/. If we work on a question during office hours, then it will appear on that page.