# Monday January 22nd

## Plotting in Julia

## Spent today plotting in Julia

- Wrote a function and plotted X against Y

- Then plotted it. The grid on command apparently changed from
`grid("on")`

to`gr()`

. Oh..kayyy. - Also, what’s neat is that for the title, it truncates after any
`(`

, but it*will*, if you type`^`

, raise that to the power, as you would like it to do, which is nice!

## User Defined Types in Julia

- User defined types in Julia are just
*awesome*. You can add constraints, and there are`Any`

types, which are the subset of all types, and other types, such as`Abstract`

,`Concrete`

, and`Composite`

. `Any`

is the supertype of all types`Concrete`

types can hold values, such as`Int64`

or`Float64`

.`Abstract`

types cannot hold values- You can see the subtypes of a type by typing
`subtypes(T)`

, where`T`

is the specific type. - You can ask
`Float64 <: Any`

which reads “Is Float a subtype of Any?”, which is true because Any is a supertype that contains all subtypes. - I’m really enjoying it.

## Equality

- You can check types by
`===(x, y)`

or`is(x, y)`

. This does*bit-level*comparison.

## Other people

- plotted some interesting stuff like the Legendre Polynomial or the Lemniscate function. I didn’t know about Lemniscate before, so that was really interesting! I think I may have made a moving sculpture via welding before that uses some version of the concept, though (don’t ask).

## Other

- I have a list of things to get together for my sailing trip next week
- I’m going to Sparklecon this weekend!
- I’m reviewing types tonight and trying to get started on Week 3’s homework since I have a short week next week (ie on a boat)!
- I’m going to work through the final SQL section of my Udacity course, and finish up Project 1.
- I’m going to get that Julia certificate!
- I saw this
`bokeh`

function, but it looks like it may be discontinued? In particular, this issue.

## Types

- Oh, I watched this video on Julia’s Type system. It’s by Jeff Bezanson and it’s called “The State of the Type System”
- Need to learn more about
- Intersection Types (“given two types, find a type that is a subtype of both”)
- Union Types

## And that’s about it!

Written on January 22, 2018