Heres a small script I wrote to calculate the future value.
#!/usr/bin/env python
# This script calculate the future value
iv = float(raw_input("Enter initial value: "));
rate = float(raw_input("Enter interest rate: "));
times = int(raw_input("Enter the amount of years: "));
fv = iv*((1 + (rate/100))**times)
print "Final amount is: %.2f." %fv
Below is the solution to Project Euler problem 92. Its written in python and takes about 10 minutes to reach the solution depending on your hardware. There are some comments in the code to know what the program is doing.
#!/usr/bin/env python
number_89 = 0
for z in range(10000000, 1, -1):
def chain(z):
var = z
chaindigit = 0
while (chaindigit != 1 or chaindigit != 89):
# Transform the number into a string
list = [int(i) for i in str(var)]
# Multiply each list member
chain = [x * y for x, y in zip(list, list)]
# Add the remaining list members
chaindigit = sum(chain)
var = chaindigit
# Check whether it ends in 89 or 1
if (chaindigit == 1 or chaindigit == 89):
# If it ends in 89 increment the value of number_89
if (chaindigit == 89):
global number_89
number_89 = number_89 + 1
break
chain(z)
print "There are", number_89,"chain numbers that end in 89."
So I finished problem 12 from Project Euler. I made it via a brute force attack in Perl.
#!/usr/bin/env perl
use warnings;
use strict;
my $j = 0;
for (my $x=1; $x <= 1000000; $x++) {
$j = $j + $x;
my $dividend = 0;
print "j is $j, x is $x and dividend is $dividend.\n";
for (my $z=1; $z <= ($j + 1); $z++) {
if ($j%$z == 0) {
$dividend = $dividend + 1;
print "$z is dividend of $j and $j has dividend $dividend.\n";
if ($dividend > 501) {
print "$z is dividend of $j and $j has dividend $dividend.\n";
exit; }
}
}
}
and with some logic in Python. The python script can be divided in three part, first we find the triangle number, then we calculate the numbers that factor the triangle number and place it into an array and the last step would be to calculate how many divisors the triangle number has.
#!/usr/bin/python
import math
# Start the triangle by one
triangle = 0
for x in range(1, 100000):
triangle = x*(x+1)/2
#print "triangles is ", triangle
# We factor the triangle into prime numbers
def primefactors(x):
factorlist=[]
loop=2
while loop<=x:
if x%loop==0:
x/=loop
factorlist.append(loop)
else:
loop+=1
return factorlist
#print primefactors(triangle)
# We calculate the number of divisors of the triangle number
divisor = 1
for z in set(primefactors(triangle)):
#print "{0}\t{1}".format(z,primefactors(triangle).count(z))
divisor = (primefactors(triangle).count(z) + 1) * divisor
#print "Triangle", triangle," has ", divisor," divisors."
if (divisor > 500):
print "Triangle", triangle," has ", divisor," divisors."
quit()
Reference:
1) Integer Factorization
2) Triangular numbers
3) Number of divisors of a number
So the other day I performed an upgrade of MySQL on a linode and notice that it wont start if I kept my old my.cnf file.
[11:47:06] user@linode1: ~ $ echo 'SHOW VARIABLES LIKE "%version%";' | mysql -u username -ppassword | grep innodb innodb_version 5.5.31 [11:47:20] user@linode1: ~ $
131022 08:17:56 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 131022 8:17:56 [ERROR] An old style --language value with language specific part detected: /usr/share/mysql/english/ 131022 8:17:56 [ERROR] Use --lc-messages-dir without language specific part instead. 131022 8:17:56 [Note] Plugin 'FEDERATED' is disabled. 131022 8:17:56 InnoDB: The InnoDB memory heap is disabled 131022 8:17:56 InnoDB: Mutexes and rw_locks use GCC atomic builtins 131022 8:17:56 InnoDB: Compressed tables use zlib 1.2.7 131022 8:17:56 InnoDB: Using Linux native AIO 131022 8:17:56 InnoDB: Initializing buffer pool, size = 128.0M 131022 8:17:56 InnoDB: Completed initialization of buffer pool 131022 8:17:56 InnoDB: highest supported file format is Barracuda. 131022 8:17:56 InnoDB: Waiting for the background threads to start 131022 8:17:57 InnoDB: 5.5.31 started; log sequence number 1678395 131022 8:17:57 [ERROR] /usr/sbin/mysqld: unknown variable 'master-host=192.168.140.120' 131022 8:17:57 [ERROR] Aborting
Thing is the replication entries in my.cnf need to be removed/commented out and salve needs to be set up from MySQL console.
So here is my new my.cnf.
[11:34:25] xavi@linode1: ~ $ sudo grep -v “^#” /etc/mysql/my.cnf | grep -v “^$”
[client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] server-id = 2 user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp language = /usr/share/mysql/english skip-external-locking bind-address = 192.168.137.234 key_buffer = 16M max_allowed_packet = 16M thread_stack = 128K thread_cache_size = 8 myisam-recover = BACKUP query_cache_limit = 1M query_cache_size = 16M expire_logs_days = 10 max_binlog_size = 100M [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] [isamchk] key_buffer = 16M !includedir /etc/mysql/conf.d/
[11:34:37] xavi@linode1: ~ $
We load the above file or similar depending on your configuration. Now to configure slave we log into the MySQL CLI.
mysql> STOP SLAVE;
mysql> CHANGE MASTER TO MASTER_HOST=’192.168.140.120′, MASTER_USER=’replication-user’, MASTER_PASSWORD=’password’, MASTER_LOG_FILE=’mysql-bin.000747′, MASTER_LOG_POS=75797;
mysql> START SLAVE;
[/text]
That’s it.
Back around here. Quick post of a small script to create A and PTR dns records.
Input file. First column is the IP and second column is the fqdn. We call this file hosts.txt
10.124.12.34 athletic.abc.com
192.158.21.32 deportivo.abc.com
92.32.43.12 drac1.abc.com
Script below:
#!/bin/bash
while read line; do
IP=`echo $line | awk '{print $1}'`
HOST=`echo $line | awk '{print $2}'`
PTR=`echo "${IP}" | awk -F\. '{print $4"."$3"."$2"."$1".in-addr.arpa."}'`
echo "${HOST}. IN A ${IP}"
echo "${PTR} IN PTR ${HOST}."
done < hosts.txt
Execution:
me@server:/tmp$ bash dnsconverter.sh
athletic.abc.com. IN A 10.124.12.34
34.12.124.10.in-addr.arpa. IN PTR athletic.abc.com.
deportivo.abc.com. IN A 192.158.21.32
32.21.158.192.in-addr.arpa. IN PTR deportivo.abc.com.
drac1.abc.com. IN A 92.32.43.12
12.43.32.92.in-addr.arpa. IN PTR drac1.abc.com.
me@server:/tmp$