Gliding Phenomena

PHP: exec command to get std errors

By appending 2>&1 at the end of the command will redirect errors from stderr to stdout.
Example:
If you run a simple command like cc at the command prompt, you would get the output as following

 $ cc  
 i686-apple-darwin10-gcc-4.2.1: no input files  
 $

If u run the same command using PHP exec command

 $cmd = "cc";  
 exec($cmd,$out);  
 print_r($out);

The output would be and empty array:

 Array ( )

So, In order to get the error string as well, we need to append 2>&1

 $cmd = "cc 2>&1";  
 exec($cmd,$out);  
 print_r($out);

The output will print:

 Array ( [0] => i686-apple-darwin10-gcc-4.2.1: no input files )

Mac: location of Apache web server logs

The following location contains error_log for apache web server in Mac machines

 /var/log/apache2/

Mac: Flush DNS cache in Snow Leapord

Run the following command in the terminal
sudo dscacheutil -flushcache

For Windows:
ipconfig /flushdns

HTML: Open link in a new window

The key to use is target="_blank"
Eg:


 <a  target="_blank" href="http://glidingphenomena.blogspot.com/">
My Blog
</a>

MySQL : Sort by Date and Time together when there are in different columns

Suppose you have date and time in two different columns of your table.
We can sort date and time together by using the ADDTIME function.

 select * from mytable ORDER BY ADDTIME(mydate, mytime);

You can also use the ADDTIME in the select clause to get data and time together.

 select ADDTIME(mydate, mytime), city from mytable

jQuery : Scroll to top/bottom of a specific DIV

Scroll to the bottom of the div:

 $jq('#divWithOverflowAuto').animate({   
         scrollTop: $jq('#divWithOverflowAuto')[0].scrollHeight}  
      );  
 }

Or you can use:

 $jq('#divWithOverflowAuto').animate({   
   scrollTop: $jq('#divWithOverflowAuto').attr('scrollHeight')}  
 );  
}

Scroll to the top of the div:

 $jq('#divWithOverflowAuto').animate({   
         scrollTop: 0 }  
      );  
 }

Matlab: Vector product, multiply 2 column matrices, "element-wise" multiplication

If we have 2 column matrices A, B.
>>A = [10;20;30]
A =
10
20
30

>> B = [1;2;3]
B =
1
2
3

>> A+B
ans =
11
22
33

>> A*B
??? Error using ==> mtimes
Inner matrix dimensions must agree.

In order to perform "element-wise" operations, we have to use ".", so for multiplication ".*", division "./"

>> A.*B
ans =
10
40
90

>> A./B
ans =
10
10
10

CakePHP : Error: The requested address “/” was not found on this server

I was moving my cakephp application to a new server and had this issue: Error: The requested address “/” was not found on this server.

The following keys might resolve your issue:

1. Check your DATABASE_CONFIG (/app/config/database.php)
2. Delete all the cache files from all of your tmp subfolders (/app/tmp)
3. Make sure your /app/tmp folder (and all of its sub folders) are writable

If you still have issues with the app, you might have to change the debug switch to 2 or 3 in the /app/config/core.php

Find the line which says "Configure::write" and replace with the following:
Configure::write('debug', 3);

This would spit all the errors on your webpage. You can debug from there.

Mac: removing known hosts/ ssh-rsa keys /RSA key fingerprint.

1. Open known_hosts file located at /Users/username/.ssh/known_hosts or ~/.ssh/known_hosts
2. Delete the CONTENTS of the file.

Since .ssh is a hidden folder, you can show/hide hidden folders using directions at mac-showhide-files-in-mac

Kernighan’s Law !

"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it."

Comparing Intel Core i3, i5, i7 processors

Intel Core i3
• Dual Core processor
• Hyper Threading Support (HT)
• Due to HT, this has 2 virtual cores.
• 2 physical cores, 2 virtual cores
• Turbo Boost (dynamic overclocking)
• Integrated graphics processor
• Fabrication : 32nm technology

Intel Core i5 – Dual Core
• Dual Core Processor
• Hyper Threading Support (HT)
• Due to HT, this has 2 virtual cores.
• 2 physical cores, 2 virtual cores
• Turbo Boost (dynamic overclocking)
• Integrated graphics processor
• Fabrication : 32nm technology

Intel Core i5 – Quad Core
• Quad Core Processor
• 4 physical cores.
• Turbo Boost (dynamic overclocking)
• Fabrication : 45nm technology

Intel Core i7
• Quad Core Processor
• Hyper Threading Support (HT)
• Due to HT, this has 8 virtual cores
• 4 physical cores, 8 virtual cores
• Turbo Boost Technology
• Fabrication : 45nm technology

Intel Core i7-980X and i7-970 have 6 physical cores and 12 virtual cores.

CakePHP: Multiple Inserts - Insert multiple rows using single statement.

Using the method saveAll(), we can achieve the desired goal. http://book.cakephp.org/view/75/Saving-Your-Data

Example:
If you want to save multiple records/rows into the same table.


$multipleRowData = Array(   
 Array('name' => 'Bob', 'phone' => "123-123-7777"),  
 Array('name' => 'Ann', 'phone' => "987-123-5555"),  
 Array('name' => 'Tom', 'phone' => "788-123-4569")  
 );   
 $this->Mymodelname->saveAll($multipleRowData);

This would result in inserting 3 rows in the "mymodelname" table.

CakePHP: Adding/deleting columns in the database after the application is Baked

If you had already baked the application and now if you made changes to the database by adding or deleting columns, then do the following:

1. Open "core.php" located at : app/config/core.php
2. Find the line which looks like: Configure::write('debug', 0);
3. Change it to Configure::write('debug', 2);
4. Refresh your application webpage.
5. Reset the line in core.php to Configure::write('debug', 0);

What basically this will do is refreshing the "model" cache.
Changing the debug level will ensure that all your databases changes are reloaded.

Following are the notes related to which debug level, you want to set.
/**
* CakePHP Debug Level:
*
* Production Mode:
* 0: No error messages, errors, or warnings shown. Flash messages redirect.
*
* Development Mode:
* 1: Errors and warnings shown, model caches refreshed, flash messages halted.
* 2: As in 1, but also with full debug messages and SQL output.
* 3: As in 2, but also with full controller dump. (NOTE: Not in CakePHP 1.3)
*
* In production mode, flash messages redirect after a time interval.
* In development mode, you need to click the flash message to continue.
*/

jQuery: Count number of visible divs

 $("div:visible").length  
 or  
 $("div:visible").size()

If we need for a specific 'class', then

 $(".myclass div:visible").length  
 or  
 $(".myclass div:visible").size()

HTML : Easiest way to create simple tooltips

Tooltips are the ones which appear as little bubbles with text, when you mouse hover over an item on Web-page.

In HTML, it is very easy to create them.

Simply add 'title' attribute to the element.

Examples:


<a title="Tooltip for Anchor !" href="someLink" >Gliding Phenomena Blog </a>

<img title="Tooltip on an Image..." src="myPic.jpg"  />

<div title="This is tooltip for the entire DIV">

Some content.

Blah 

Blah

</div>

SQL : Update only year in the date field

UPDATE mytable
SET datefield = CONCAT('2012','-',MONTH(datefield),'-',DAYOFMONTH(datefield))
WHERE YEAR(datefield) = 2006;

Javascript: Regex for Email Validation


function isValidEmail(email){
 var emailRegx = /^([a-zA-Z0-9_.-])+@([a-zA-Z0-9_.-])+\.([a-zA-Z])+([a-zA-Z])+/;
 return emailRegx.test(email);
}

Mac: Show/hide Hidden files in Mac OS

To Show Hidden files run the following 2 commands in the terminal

defaults write com.apple.finder AppleShowAllFiles TRUE

killall Finder

To Hide Hidden files run the following 2 commands in the terminal.

defaults write com.apple.finder AppleShowAllFiles FALSE

killall Finder

Draw Smooth Circles in JAVA instead of jagged edge circles.

Usually when we draw circles/ovals using Graphics2D in JAVA, we get jagged edges.
Following example creates smooth edges to the circle.
The key is g2d.setRenderingHint (RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);


import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;

public class DrawSmoothCircle {
public static void main(String[] argv) throws Exception {
BufferedImage bufferedImage = new BufferedImage(100,100, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = bufferedImage.createGraphics();

g2d.setRenderingHint (RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setPaint(Color.green);
g2d.fillOval(10, 10, 50, 50);
g2d.dispose();

ImageIO.write(bufferedImage, "png", new File("newimage.png"));
}
}

Multidimensional Scaling (MDS) Basic Tutorial, Introduction

A very pleasant and quick introduction to Multidimensional(MDS) scaling can be found at

http://homepages.uni-tuebingen.de/florian.wickelmaier/pubs/Wickelmaier2003SQRU.pdf

http://www.tonycoxon.com/KUB/mds_menu.htm