51 lines
No EOL
2.2 KiB
Markdown
51 lines
No EOL
2.2 KiB
Markdown
**MatRepl**
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* is a Matrix
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* and a repl: Read–Eval–Print Loop, where Print is doing operations on vectors and matrices in a graphic environment
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* written in vanilla javascript (ES6)
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The repl has the following syntax (It's work in progress, new capabilities will be added)
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* arithmetic expressions:
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* add(+), subtract(-), divide(/), multiply(*) on scalars, vectors and matrices.
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* variable declaration eg: ```a = 1 + 2```
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* ```remove(x)``` removes bindings (when it's an object (eg vector), removes it from the matrix)
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* ```remove(@n)``` removes an object using it's assigned index (```n``` is a number)
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* By the way, values can be bound to a name (assigned to a variable), but you can always also refer to them using their id, using : ```@n```
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* so ```a = vector(1,1)```
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> > vector@0{x0:0, y0: 1, x:1, y:1}
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* and then ```@0```
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> > vector@0{x0:0, y0: 1, x:1, y:1}
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* method calls:
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```a = vector(12, 1)```
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> > vector@0{x0:0, y0: 2, x:12, y:1}
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* ```vector(1 2)``` works as well. The start is now the origin.
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commas are not mandatory. I'm planning to add a more mathematical notation for vectors: ```[1 2]```
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* properties
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* ```a = vector(12, 1)```
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* ```a.type```
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> > vector
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* ```a.x+1```
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> > 13
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* drag vectors using the mouse pointer. You can change the vector arrows visually
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* lazy evaluation. The difference between ```c = a+b``` and ```c = "a+b"```
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is that the latter assigns to ```c``` a parsed expression that can always be evaluated later.
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When you apply lazy evaluation and later update ```a```, the value for c will be reevaluated
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automatically. Combined with vector dragging, this way you can get an intuition for vector addition.
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Want to do the same for matrix multiplication and basis change.
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* Example: enter the following, like in the screenshot:
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```
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a = vector(0.5, 0.5)
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b = vector(-1, 1)
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c = "a + b"
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```
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* and press enter. Then using the mouse pointer move vector ```a``` or ```b```. Or try: ```a = 2 * a```
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This updates vector ```a``` to twice it's size. And, because ```c``` is defined lazily, it is updated as well!
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**To run locally**
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* make sure you have node/npm
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* cmdline: npm run start
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* and enter ```help()``` |