modular-x

Define once. Substitute anytime. Compute instantly.

Table of contents:

• Description
• Usage
• Core featurs
  • Actions
  • Using Variabels
  • Multiplying
  • Functions
• Packages Used

Description

This CLI allows the you to write and store expressions (e.g., 2x^2 - 3) under any chosen name.

At any given time, you can replace the variables in the expression with numbers (e.g., x = 3) and solve them instantly.

The expressions can range from basic addition, subtraction, multiplication and division to the pythagorean theorem and quadratic formula.

Usage

  npx modular-x

Core features

Actions

The user has 6 actions.

Note:
the user will always be prompted to select an action from a list of options upon running the CLI.

• List: lists all the stored expressions.

• Create: create a new expression and give it name (e.g., euclidean distance). The user will then be prompted to input its content (e.g., (x2 - x1)^2 + (y2 - y1)^2), which will then be stored.

• Edit: Edit the content of an existing expression (e.g., from x + y -> x^2 + y), by inputting it's name and its new content in subsequent prompts.

  Note:
  the old content will be the placeholder for the new content input prompt so use tab key to auto-fill the prompt with it

• Solve: user inputs a name of an existing expression and is then prompted to replace variables in the expression with numbers. The expression, now with numbers, is then solved and the input is returned.

  Note:
  

  • replacing varibales does not modify the stored expression.
  • varibles can either be replace by numbers or expression, but expressions need to be enclosed in parentheses.
  • variable substitues cannot contain letter (e.g., you cannot replace x with (y + 1) or y)

• Rename: change the name of an existing expression (e.g., to John Doe). You have complete control!

• Delete: permanently delete an existing expression.

Using Variables

• Variables must always be a letter (e.g, x or y) and can either be upper or lowercase
• Identifiers (will be referred to as id): follow a letter with only a number (the id) when wanting to use the same letter for variables that have different values (e.g., to show they are related).

Examples:

  xx //the 2 x variables are considered the same--they have the same letter and no id

  x2 + x2x2 //the 3 x variables are considered the same--they have the same letter and id
      
  x222x  //x and x will be considered different variables because one has an id
      
  x233 + x2  //the 233 and 2 are used as ids to count the 2 x variables as different

  (x2 - x1)^2 + (y2 - y1)^2 //each x and y variable is considered unique because of their ids
        

Multiplying

When multiplying a pair of anything, one can simply use [number/variable] * [number/variable].

If the first thing in the pair, is a number, variable or bracket, and the second is a variable or bracket, you can ommit the *. Note: they must have no spaces between them!

Examples: (-> means auto-changed to)

  xyz -> x*y*z

  2xx3 -> 2*x*x3

  2(x + 3) -> 2*(x + 3)

  (X + Y)Z -> (X + Y)*Z
          
  (x - y)(x2y4x) -> (x - y)*(x2*y4*x)

  x333 //333 is considered an id for the variable

Functions

Note:

• all funcitons must be preceeded by a semi column : (e.g., :sin(x))
• they can be preceeded by a number or letter when multiplying (e.g., 2:pi -> 2 * : pi)
• all functions that are followed by () must have an expression/variable/number in between the parentheses (e.g. 3:sin(x + 1) )

• pi: returns the value of pi; Usage examples:

    :pi -> 3.141... 
    2:pi * r -> 6.282 * r
  

functions below are used in the same way as each other (though they return different values)

• sin(): Returns the sine of the expression/variable/number in parentheses. Usage examples

    2:sin(x + 2) -> 2 * sin(x + 2)
    :sin(x - 3)(5 + 2) -> sin(x - 3)*(5-2)
  

  Note:
  The value of the expression/number/value is always considered to be in radians

• sinh(): returns the hyperbolic sine of the expression/variable/number (in radians) in parentheses.
• asin(): returns the arcsine of the expression/variable/number (in radians) in parentheses.
• asinh(): returns the hyperbolic arcsine of the expression/variable/number (in radians) in parentheses.

• cos(): returns the cosine of the expression/variable/number (in radians) in parentheses.

• cosh(): returns the hyperbolic cosine of the expression/variable/number (in radians) in parentheses.

• acos(): returns the arccosine (inverse cosine) of the expression/variable/number (in radians) in parentheses.

• acosh(): returns the hyperbolic arccosine of the expression/variable/number (in radians) in parentheses.

  
  

• tan(): returns the tangent of the expression/variable/number in parentheses.

• tanh(): returns the hyperbolic tangent of the expression/variable/number (in radians) in parentheses.

• atan(): returns the arctangent (inverse tangent) of the expression/variable/number (in radians) in parentheses.

• atanh(): returns the hyperbolic arctangent of the expression/variable/number (in radians) in parentheses.

  
  

• log(): returns the natural logarithm (base e) of the expression/variable/number in parentheses.

• logt(): returns the base 10 logarithm of the expression/variable/number in parentheses.

Packages used:

• Clack: for the appearance of the cli.
• fs: for creating and deleting files for storing expressions