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Maths and Computing JavaScript Examples
This tool will run small JavaScript programs. It is essentially intended for use with the book "An Introduction to Mathematics for Computing and IT Practitioners". Click an entry on the right to select one of the book's code examples.
1.3.2: Working out the triangular numbers
2.3.1: Storing a vector in an array
2.3.2: Storing a matrix in an array
3.2.3: Multiplying two 2 by 2 matrices
5.3.2: Solving a simultaneous equation
6.4.2: Finding the minimum spanning tree
7.5.1: Calculating the nth term of a given sequence V1
7.5.2: Calculating the nth term of a given sequence V2
8.2.2: Quick Sort
9.6.3: Simulation Scenario 1
9.6.4: Simulation Scenario 2
11.1.5: Converting a decimal number to binary
11.5.3: Converting binary numbers to Gray code
13.4.3: Converting an 8-bit character to MIME Base 64
15.1.2: Calculating a sequence of prime numbers
15.2.3: Euclids Algorithm
15.3.2: Calculating the square root of a binary number
15.5.2: Working out the day of the week
<html>
<body>
<script type ="text/javascript"> <title>
Calculating a sequence of prime numbers
</title>
</head>
<body>
<script type ="text/javascript">
// Find the prime numbers between 1 and 100 // Set n to the value 100 n = 100; // Initialise the array of bit values primes = new Array(n+1); primes[1]=0; for(i=2; i<=n; i++) { primes[i]=1; } // Find the square root of n sroot = Math.floor(Math.sqrt(n)); // Check each value from 2 to sroot for(i=2; i<=sroot; i++) { // Check to see if the current value is a prime if(primes[i]==1) { // Find the multiples of i for(j=2*i; j<=n;j=j+i) { // Set the array value to 0 primes[j]=0; } } } // Display the prime numbers for(i=1;i<=n;i++) { if(primes[i]==1) { document.writeln(i + "
"); } }
</script>
</body>
</html>