Forem: Santhosh Kumar

fcal -Extensive math expression evaluator library for JavaScript and Node.js

Santhosh Kumar — Fri, 23 Oct 2020 09:24:48 +0000

🏠 Homepage

Fcaljs is an extensive math expression evaluator library for JavaScript and Node.js.
Using fcal, you can perform basic arithmetic, percentage operations with precision.
It features a flexible expression parser with a large set of built-in units, functions and constants.
Inspired from Numi

Features

Units
Variables
Functions

Playground Fcal GUI, Codepen , CLI

Example

const fcal = new Fcal();
// New variable
fcal.evaluate('radius : 23 m'); // 23 Meters

fcal.evaluate('PI * radius ^ 2'); // 1661.9025137490006231 Meters

fcal.evaluate('PI2 * radius'); // 144.51326206514 Meters

// Predefined functions
fcal.evaluate('log(23)'); // 1.3617278360175928789

// Percentage
fcal.evaluate('23 % of 1023'); // 235.29

fcal.evaluate('200 sec + 120 %'); // 440 Seconds

// Unit conversion
fcal.evaluate('20 minutes + 34 day in sec'); // 2938800 Seconds

fcal.evaluate('sin(PI)'); // -1.6167204971158028306e-24

// Constants
fcal.evaluate('E'); // 2.718281828459045235360287

// Predefined units
fcal.evaluate('speed = 20 kph'); // 20 km/h

fcal.evaluate('speed in mps'); // 5.5555555555555555556 m/s

fcal.evaluate('23 C add 123 F'); // 196.40000000000004 °F

fcal.evaluate('1.2 nsec + 3 week in sec'); // 1814400.0000000012 Seconds

// Various number system
fcal.evaluate('0b1010011 day + 45'); // 128 Days

fcal.evaluate('23.44 kmh in oct'); //  0o27.341217270243656051 km/h

Install

Browser

the library is the single JavaScript file fcal.js (or minified, fcal.min.js).

<script src="https://cdn.jsdelivr.net/npm/fcal/dist/fcal.js"></script>

With NPM

$ npm install --save fcal

const { Fcal } = require('fcal');

Use

const { Fcal } = require('fcal');

const fcal = new Fcal();
var value = fcal.evaluate('102 day in minutes + abs(-34 day) in sec');

console.log(value); // 11750400 Seconds

Percentage

var value = fcal.evaluate('27% of 230 cm');
console.log(value); // 62.1 Centimeters

You can perform general percentage operation with + , -

var value = fcal.evaluate('1024 m + 6.1%');
console.log(value); // 1086.464 Meters

If type of left and right hand side of of is same, then operation will return percentage

var value = fcal.evaluate('10 of 10.100');
console.log(value); // % 99.009900990099009901

Scales

You can use Thousand k, million M and billion B scales.

var value = Fcal.eval('-0x14 M');
console.log(value); //-20000000

Equality and comparison

console.log(Fcal.eval('100 == 1230')); // false
console.log(Fcal.eval('20 cm < 1 m')); // true
console.log(Fcal.eval('100 cm != 100 m')); // true

You can use === to compare irrespective type of value

console.log(Fcal.eval('100 C === 100 F')); // true

Ternary operator

var value = Fcal.eval('234 cm > 1 m and true ? 34: 100');
console.log(value); // 34

Syntax errors

Fcal will throw exception if there is error with expression

For more error context, use info method in FcalError

try {
  var value = Fcal.eval('343 + 23.45E+*34');
} catch (e) {
  if (e instanceof FcalError) {
    console.log(e.info());
  }
}

/*
err: Expecting number after + but got '*'
| 343 + 23.45E+*34
| ......^^^^^^^
*/

Strict mode

By default, fcal will not throw exception if you try to use operations between different types or different units

But with strict mode

const fcal = new Fcal();
fcal.setStrict(true)
try {
  var value = fcal.evaluate('23% + 34 cm + 1');
} catch (e) {
  if (e instanceof FcalError) {
    console.log(e.info());
  }

/*
err: Unexpected '+' operation between different types (unit, number)
| 23% + 34 cm + 1
| ^^^^^^^^^^^^^^^
*/

Using expression

You can change state of expression , re evaluate it

const { Fcal } = require('fcal');

const exp = new Fcal().expression('PI * radius cm ^ 2');

exp.setValues({ radius: 8 });

console.log(exp.evaluate()); // 201.06192982974676726 Centimeters

exp.setValues({ radius: 10 });

console.log(exp.evaluate()); // 314.15926535897932385 Centimeters

exp.setValues({ radius: Infinity });

console.log(exp.evaluate()); // Infinity Centimeters

🤝 Contributing

Contributions, issues and feature requests are welcome!
Feel free to check issues page.

To contribute

$ git clone https://github.com/5anthosh/fcal

$ npm install

Run tests

$ npm test

Fcal

Santhosh Kumar — Fri, 13 Dec 2019 11:25:13 +0000

Math expression evaluator https://github.com/5anthosh/fcal

Discrete mathematics

Santhosh Kumar — Wed, 27 Nov 2019 06:25:41 +0000

Discrete mathematics is part of mathematics devoted to study of discrete objects (distinct or unconnected object)

Why

Ability to understand and create mathematical arguments
Provides foundation for many computer science courses including data structures, algorithms, compiler design, etc;

What kind of problems can be solved by discrete mathematics

How many ways to choose valid password on a computer system?
How many steps is required to do such sorting ?
How can it proved that sorting algorithm correctly sorts a list?
How many valid internet addresses are there ?

Logic and proof

Logic

The rules of logic specify the meaning of mathematical statements and helps us understand and reason with statements such as
There exists number which is not sum of two squares,
For every positive integer n, sum of positive integers not exceeding n is n*(n+1)/2.
Logic is basis for all mathematical reasoning and computed reasoning.

Proof

To understand mathematics, we must understand what makes up a correct mathematical argument, that is proof.
One we prove mathematical argument is true, we call a theorem, a collection of theorem on a topic organize what we know about a topic.
Proofs are used to verify that computer program produce correct output for all possible input values to show that algorithm always produce correct result
to establish security of the system.

fcal - Math expression evaluator in Javascript

Santhosh Kumar — Thu, 07 Nov 2019 12:20:24 +0000

🏠 Homepage

Fcaljs is an extensive math expression evaluator library for JavaScript and Node.js.
Using fcal, you can perform basic arithmetic, percentage operations with precision.
It features a flexible expression parser with a large set of built-in units, functions and constants.
Inspired from Numi

Features

Units
Variables
Functions

Playground Codepen , CLI

Example

const fcal = new Fcal();
// New variable
fcal.evaluate('radius : 23 m'); // 23 Meters

fcal.evaluate('PI * radius ^ 2'); // 1661.9025137490006231 Meters

fcal.evaluate('PI2 * radius'); // 144.51326206514 Meters

// Predefined functions
fcal.evaluate('log(23)'); // 1.3617278360175928789

// Percentage
fcal.evaluate('23 % of 1023'); // 235.29

fcal.evaluate('200 sec + 120 %'); // 440 Seconds

// Unit conversion
fcal.evaluate('20 minutes + 34 day in sec'); // 2938800 Seconds

fcal.evaluate('sin(PI)'); // -1.6167204971158028306e-24

// Constants
fcal.evaluate('E'); // 2.718281828459045235360287

// Predefined units
fcal.evaluate('speed = 20 kph'); // 20 km/h

fcal.evaluate('speed in mps'); // 5.5555555555555555556 m/s

fcal.evaluate('23 C add 123 F'); // 196.40000000000004 °F

fcal.evaluate('1.2 nsec + 3 week in sec'); // 1814400.0000000012 Seconds

// Various number system
fcal.evaluate('0b1010011 day + 45'); // 128 Days

fcal.evaluate('23.44 kmh in oct'); //  0o27.341217270243656051 km/h

Install

Browser

the library is the single JavaScript file fcal.js (or minified, fcal.min.js).

<script src="https://cdn.jsdelivr.net/npm/fcal/dist/fcal.js"></script>

With NPM

$ npm install --save fcal

const { Fcal } = require('fcal');

Use

const { Fcal } = require('fcal');

const fcal = new Fcal();
var value = fcal.evaluate('102 day in minutes + abs(-34 day) in sec');

console.log(value); // 11750400 Seconds

Percentage

var value = fcal.evaluate('27% of 230 cm');
console.log(value); // 62.1 Centimeters

You can perform general percentage operation with + , -

var value = fcal.evaluate('1024 m + 6.1%');
console.log(value); // 1086.464 Meters

If type of left and right hand side of of is same, then operation will return percentage

var value = fcal.evaluate('10 of 10.100');
console.log(value); // % 99.009900990099009901

Scales

You can use Thousand k, million M and billion B scales.

var value = Fcal.eval('-0x14 M');
console.log(value); //-20000000

Equality and comparison

console.log(Fcal.eval('100 == 1230')); // false
console.log(Fcal.eval('20 cm < 1 m')); // true
console.log(Fcal.eval('100 cm != 100 m')); // true

You can use === to compare irrespective type of value

console.log(Fcal.eval('100 C === 100 F')); // true

Ternary operator

var value = Fcal.eval('234 cm > 1 m and true ? 34: 100');
console.log(value); // 34

Syntax errors

Fcal will throw exception if there is error with expression

For more error context, use info method in FcalError

try {
  var value = Fcal.eval('343 + 23.45E+*34');
} catch (e) {
  if (e instanceof FcalError) {
    console.log(e.info());
  }
}

/*
err: Expecting number after + but got '*'
| 343 + 23.45E+*34
| ......^^^^^^^
*/

Strict mode

By default, fcal will not throw exception if you try to use operations between different types or different units

But with strict mode

const fcal = new Fcal();
fcal.setStrict(true)
try {
  var value = fcal.evaluate('23% + 34 cm + 1');
} catch (e) {
  if (e instanceof FcalError) {
    console.log(e.info());
  }

/*
err: Unexpected '+' operation between different types (unit, number)
| 23% + 34 cm + 1
| ^^^^^^^^^^^^^^^
*/

Using expression

You can change state of expression , re evaluate it

const { Fcal } = require('fcal');

const exp = new Fcal().expression('PI * radius cm ^ 2');

exp.setValues({ radius: 8 });

console.log(exp.evaluate()); // 201.06192982974676726 Centimeters

exp.setValues({ radius: 10 });

console.log(exp.evaluate()); // 314.15926535897932385 Centimeters

exp.setValues({ radius: Infinity });

console.log(exp.evaluate()); // Infinity Centimeters

🤝 Contributing

Contributions, issues and feature requests are welcome!
Feel free to check issues page.

To contribute

$ git clone https://github.com/5anthosh/fcal

$ npm install

Run tests

$ npm test

best practices in publishing npm package

Santhosh Kumar — Mon, 14 Oct 2019 05:24:20 +0000

I am working on this side project fcal

I want to release it as npm package , but I also want it to act as cli.

Should I create another npm package for cli or npm package acts as (both) cli and module ?

I am new to nodejs environment and learning best practices

thanks !

Lets make errors in Go traceable

Santhosh Kumar — Fri, 30 Aug 2019 08:20:19 +0000

I wrote a module to make Go traceable

just attaching README here :-)
oops

oops 🙊

oops makes errors in Go traceable.
It provies traceback function to get more information when you return error from the function

The convention says that an error should either be handled (whatever that means) or returned to the caller.
But with more abstraction, it is difficult to find where the error got originated
so Traceable function returns error with more information

Example

package main

import (
    "errors"

    "github.com/5anthosh/oops"
)

func main() {
    err := func1().(*oops.Error)
    println(err.Skip(1).Error())
}

func func1() error {
    return func2()
}

func func2() error {
    return func3()
}

func func3() error {
    return oops.T(errors.New("dummy one")).Info("this is just testing")
}

Run the program

$ go run test.go
🔴  Error : dummy one
ℹ️   Info  : this is just testing
         at main.func3 line 23 Desktop/Files/test.go
         at main.func2 line 19 Desktop/Files/test.go
         at main.func1 line 15 Desktop/Files/test.go
         at main.main line 10 Desktop/Files/test.go

Could not fine vscode api to create like 'SCM working tree'

Santhosh Kumar — Mon, 15 Jul 2019 12:46:16 +0000

I like to create to window like 'SCM working tree' window which appears in git changes

I need help with vscode api because I could not find it

please let me know if you know the vscode api or how to create it

thanks

Golang server load

Santhosh Kumar — Sun, 10 Mar 2019 02:37:42 +0000

I want to calculate number of requests per second (server load) of my application in golang

can you suggest any tool ?

thanks

Redis session store architecture

Santhosh Kumar — Fri, 08 Mar 2019 08:13:04 +0000

Hey, I am building IOT platform , for that I need to use redis as session management

use api token to get user details
use user id to get all api tokens of the user

I am new redis,so need suggestion to build this session management

Websocket

Santhosh Kumar — Wed, 06 Mar 2019 11:02:28 +0000

With webSockets you have a stateful request /response system, how can we store websocket connection reference in the server such that we can have stateless system ?

JAVASCRIPT: DATA TYPES

Santhosh Kumar — Wed, 27 Feb 2019 05:22:09 +0000

This post was originally published on my blog, find original post here

Every variable has a data type that determines type of value it stores, a variable of type number can store an integer or floating-point numbers.

JavaScript is dynamically typed language which means a variable can be number type for a moment and at another be a string type.

Number

number type represents both integer and fractional (floating point numbers).

let num = 79; // integer
let num = 65.45; // floating-point

We can perform arithmetic operations like +, -, *, /.

let num = 45 + 2 * 6; // 57

For very big number or very small number, we can use e (exponent)

let speedOfLight = 2.998e8;

Infinity represents mathematical infinity, this is a special numeric value.

let infinity = 1 / 0; 
console.log(infinity); // Infinity

NaN is also a special numeric value to represent the incorrect or invalid mathematical operation.

let nan = "str" / 79;

We can get the data type of a variable using typeof.
console.log(typeof "peace"); //string

String

string is used to represent text. They are written by eclosing them their content in quotes.

let hello = "Hello World";
let sq = 'sinle quote';

Both single quote and double quote can be used.

Backticks represents string template, we can embed variable and expression in a string by enclosing them in ${ variable or expression }
expression inside ${....} is evaluated and becomes a part of the string.

let name = "Kevin";
console.log(`My name is ${ name } `); // My name is kevin
console.log(`Age is ${17 + 1} `); // Age is 18

Boolean

Boolean type has two values only: true and false.

It is used to store yes/ no values.

let isGreater = true;

null

To represent nothingness, empty, we can use null

let answer = null;

undefined

if a value is not assigned to a variable or variable is not declared , it will have undefined .

Meaning of undefined is "value is not assigned".

let a;
console.log(a) //undefined

DEVELOPER CONSOLE

Santhosh Kumar — Tue, 26 Feb 2019 05:55:58 +0000

This post was originally published on my blog, find original post here

Wether you want to try some JavaScript function , inspect a JavaScript Object or see if there is any errors.
Developer console (web console) is here to help you

Developer Console

Most modern browser provides developer console where you can play with JavaScript in shell like interface.

we can open web console with the keyboard shortcut CTRL + SHIFT + K on Linux and Windows, or COMMAND + OPTION + K on macOS.

we can enter a JavaScript command, examine variables and declare function.

logging in JavaSript can be achieved using console.log function

We can add multi-line JavaScript command using SHIFT + ENTER