Difference between revisions of "Prime factorization"
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| + | <metadesc>Mesham is a type oriented programming language allowing the writing of high performance parallel codes which are efficient yet simple to write and maintain</metadesc> | ||
== Overview == | == Overview == | ||
| Line 5: | Line 6: | ||
== Source Code == | == Source Code == | ||
| + | #include <io> | ||
| + | #include <string> | ||
| + | #include <maths> | ||
| + | |||
var n:=976; // this is the number to factorize | var n:=976; // this is the number to factorize | ||
| − | var m:= | + | var m:=10; // number of processes to use |
var s:Int :: allocated[multiple[]]; | var s:Int :: allocated[multiple[]]; | ||
| − | var p; | + | function void main() { |
| − | + | var p; | |
| − | + | par p from 0 to m - 1 { | |
| − | + | var k:=p; | |
| − | + | var divisor; | |
| − | + | var quotient; | |
| − | + | while (n > 1) { | |
| − | + | divisor:= getprime(k); | |
| − | + | quotient:= n / divisor; | |
| − | + | var remainder:= n % divisor; | |
| − | + | if (remainder == 0) { | |
| − | + | n:=quotient; | |
| − | + | } else { | |
| − | + | k:=k + m; | |
| − | + | }; | |
| − | + | s :: allreduce["min"]:=n; | |
| − | + | if ((s==n) && (quotient==n)) { | |
| − | + | print(itostring(divisor)+"\n"); | |
| − | + | }; | |
| − | + | n:=s; | |
| − | + | }; | |
| − | + | }; | |
| − | |||
| − | |||
}; | }; | ||
| + | |||
| + | ''This code requires at least Mesham version 1.0'' | ||
== Notes == | == Notes == | ||
| Line 41: | Line 46: | ||
== Download == | == Download == | ||
| + | |||
| + | You can download the prime factorization source code [http://www.mesham.com/downloads/fact.mesh here] and a legacy version for Mesham 0.5 is also available [http://www.mesham.com/downloads/fact-0.5.mesh here] | ||
| + | |||
| + | [[Category:Example Codes]] | ||
Latest revision as of 15:44, 15 April 2019
Contents
Overview
This example will perform prime factorization on a number parallely, to return the prime factors which make up that number. The example uses the primitive communication, all reduce. There are actually a number of ways such a result can be obtained - this example is a simple parallel algorithm for this job.
Source Code
#include <io>
#include <string>
#include <maths>
var n:=976; // this is the number to factorize
var m:=10; // number of processes to use
var s:Int :: allocated[multiple[]];
function void main() {
var p;
par p from 0 to m - 1 {
var k:=p;
var divisor;
var quotient;
while (n > 1) {
divisor:= getprime(k);
quotient:= n / divisor;
var remainder:= n % divisor;
if (remainder == 0) {
n:=quotient;
} else {
k:=k + m;
};
s :: allreduce["min"]:=n;
if ((s==n) && (quotient==n)) {
print(itostring(divisor)+"\n");
};
n:=s;
};
};
};
This code requires at least Mesham version 1.0
Notes
Note how we have typed the quotient to be an integer - this means that the division n % divisor will throw away the remainder. Also, for the assignment s:=n, we have typed s to be an allreduce communication primitive (resulting in the MPI all reduce command.) However, later on we use s as a normal variable in the assignment n:=s due to the typing for the previous assignment being temporary.
As an exercise, the example could be extended so that the user provides the number either by command line arguments or via program input.
Download
You can download the prime factorization source code here and a legacy version for Mesham 0.5 is also available here
