cas-from-scratch

A rudimentary computer algebra system made from scratch in Rust, using no external crates/libraries.
This was made for fun/my own learning

Capabilities

• Parsing expressions
• Displaying expression trees
• Implicit graphing of equations
• Simplifying expressions

Expressions

This uses an entirely custom expression parser, so it may be more barebones than other CAS implementations

x and y are variables

Symbols:

• x + y
• x - y
• x * y
• x / y
• sin x
• cos x
• tan x
• abs x
• sqrt x
• x log y
• x ^ y
• ( x + y ) * x

Graphing

This program will print an implicit graph in the command line given two user-provided expressions.

Example

https://en.wikipedia.org/wiki/Rose_(mathematics)

Expressions in memory:
1: ( x ^ 2 + y ^ 2 ) ^ 3
2: -7.5 * ( x ^ 5 - 10x ^ 3 * y ^ 2 + 5x * y ^ 4 )

0. Quit
1. Enter an expression
2. Print expression tree
3. Compute value from expression
4. Graph expressions as equation
5. Simplify an expression
Pick an operation by number: 4
x-axis minimum (default -10):
x-axis maximum (default 10): 
y-axis minimum (default -10): 
y-axis maximum (default 10): 
x scale (default 1.0): 0.15
y scale (default 1.0): 0.3

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Simplification

This function is still WIP, and currently attempts to combines all constant values

Example

Expressions in memory: 
1: ( 15 * 2.3 ) * x - ( y + 4 - 3 ) / 3 log 9
2: 

0. Quit
1. Enter an expression
2. Print expression tree
3. Compute value from expression
4. Graph expressions as equation
5. Simplify an expression
Pick an operation by number: 5
Select an expression to simplify: 1
_______________________________________________________________________________________

Expressions in memory:
1:  ( ( 34.5 * x ) - ( ( ( y + 4 ) - 3 ) / 0.5 ) )
2:

0. Quit
1. Enter an expression
2. Print expression tree
3. Compute value from expression
4. Graph expressions as equation
5. Simplify an expression
Pick an operation by number: