Linear Algebra... perhaps not used quite as often by non-scientists/non-engineers but in those domains it's used quite a bit. An example: Control Systems. You

Linear Algebra... perhaps not used quite as often by non-scientists/non-engineers but in those domains it's used quite a bit. An example: Control Systems. You have a device that takes some inputs and has some outputs. This device is usually modeled by a nxm matrix because it has n inputs and m outputs. From there, you want to build some other device to make sure that your original device does what you want it to do. Doing all this stuff requires linear algebra. In general, linear algebra comes into play once the number of variables you're dealing with is greater than one. You mentioned that you've discovered that probability and statistics are important. Well, you'll need linear algebra to deal with that once the number of variables exceeds one. Well, perhaps 'need' is too strong a word for it, but in the presence of multiple variables linear algebra is necessary as much as, say, integration for calculating the area underneath a curve. You can get by without it, but it has many advantages and brings more to the table. Outside science/engineering domains? I can't think of anything it would be really useful for.