If you want to visit a site and get a popup with this error in Firefox 3.5, what you have to do is this:

1. Type about:config in the address bar. From the window that appears, find the following line “browser.xul.error_pages.enabled”. If the value from the same line is false, then double click it(it will turn to “true”).

2. Enter the URL of the webpage that you wanted again, a window will appear offering you the option of adding an exception that allows you to view the website.

Adding an exception can also be done manually, following the steps:

1. Go to “Tools” menu and then “Options” .
2. Click on “Advanced”, then tab “Encryption” .
3. Click on the “View Certificates” button.
4. Select the tab called “Servers” from the window that appears.
5. Click on the button “Add Exception” (bottom right).

If the POP3 access trick described in my Yahoo Mail free POP access post does not work (and because of that the method described in this post for reading Yahoo Mail  in Gmail does not work), your only option is to use a third party application.

The simplest way to read Yahoo Mail messages in your Gmail inbox is to use the free web application called Nutshellmail. Just sign up for an account, setup Gmail as your primary address and setup your yahoo account. You will start receiving your Yahoo Mail in Gmail. You can customize the hours when Nutshellmail checks for Yahoo email, but the interval cannot be less than an hour. Another disadvantage is that the messages arrive batched in a single email, but this is a small price to pay for getting the email in Gmail for free.

Amdahl’s law states that the speedup achieved through parallelisation of a program is limited by the percentage of its workload that is inherently serial. We can get no more than a maximum speedup equal to 1 / (s + p / N ) where

s = the length of the serial part of the problem

p = the length of the parallel part of the problem

N = number of processors used

Gustafson’s law states that , with increasing data size, the speedup obtained through parallelisation increases, because the parallel work increases(scales) with data size.

To those who took Amdahl’s law as an argument against Massively Parallel Processing, Gustafson’s law proves they are wrong.

1. Today, Amdahl’s presumption of fixed data size is obviously a restriction which does not map into reality for many problems.

2. Both laws are in fact different perspective over the same truth – one sees data size as fixed and the other sees the relation as a function of data size.

My compilers teacher was Preston Briggs’ teacher.
I’m happy and proud that I managed to get here.

My blog was stumbled a few days ago, and this is the result:

I always heard about such spikes in visitors / page views, but I never thought it would happen to me . Five times more visitors than the average, in one day.

I simply love it

Firefox 3.5 icon

If your Latex document has two or more columns, if you add a figure or table, it will span one column and then overlap with the text from the second one. To fix this and let the object take up space in both columns, just add a star after the object name, like this:

\begin{table*}
\centering
\caption{Table Caption}
\begin{tabular} …
\end{tabular}
\end{table*}

or, for a figure:

\begin{figure*}[!t]
\centering
\includegraphics[width=7in]{filename}
\caption{ Figure Caption}
\label{label}
\end{figure*}

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The easiest method to get the CPU usage from a Java class in Linux is to parse the output of the top command. Check out the following code.

import java.io.*;
public class SystemData
{
    static String cmdTop = "top -n 2 -b -d 0.2";
    // returns user cpu usage 
    public static double getCpu()
    {
        double cpu = -1;
        try
        {
            // start up the command in child process
            String cmd = cmdTop;
            Process child = Runtime.getRuntime().exec(cmd);

            // hook up child process output to parent
            InputStream lsOut = child.getInputStream();
            InputStreamReader r = new InputStreamReader(lsOut);
            BufferedReader in = new BufferedReader(r);

            // read the child process' output
            String line;
            int emptyLines = 0;
            while(emptyLines<3)
            {
                line = in.readLine();
                if (line.length()<1) emptyLines++;
            }
            in.readLine();
            in.readLine();
            line = in.readLine();
            System.out.println("Parsing line "+ line);
            String delims = "%";
            String[] parts = line.split(delims);
            System.out.println("Parsing fragment " + parts[0]);
            delims =" ";

            parts = parts[0].split(delims);
            cpu = Double.parseDouble(parts[parts.length-1]);
        }
        catch (Exception e)
        { // exception thrown
            System.out.println("Command failed!");
        }
        return cpu;
    }
}

The parameters from the top command line mean: -b = batch mode, -d 0.2 = take the readings at 0.2 seconds intervals, -n 2 = take 2 readings (the first reading is not correct, from my experience, so we take two).
This code fragment only gets the user CPU percentage. To get the whole CPU percentage, you have to add this value with the system CPU. These values are easy to obtain by changing a few numeric values in the above code. This is left as an exercise for the user. Note that although in general the system CPU and nice CPU percentages are very small, this is not always the case and it is safer to add these values together than to approximate the CPU usage as user CPU only.

If the company you work for has restrictions that allow visiting certain company websites only from within the company, you can bypass this restriction using ssh access.

From your local machine, connect to the ssh server of your company and add a few options, like this:

ssh -C2qTnN -D 8090 username@servername

This command will not finish, this is expected and desired. The port (in my case 8090) can be any port you want (but over 1024 if you are not root).

You have created a ssh tunnel that ca be used to tunnel the web browser traffic, so that you can see the sites that are visible from you ssh server. To do this using Firefox, go to Preferences->Advanced->Network. The window will look like the image below.

Firefox Network Options window.

Click on the “Settings” button and a configuration screen will pop up. Complete it like in the following screenshot.

Firefox Connections Settings Window. Here we direct the browser to use the ssh tunnel we created.

This is all you need to do,  you can now surf on local sites from the internet by entering the url you want in the URL bar in Firefox. Don’t forget to set “no proxy” option in the same configuration screen when you want to close the ssh window.

Using ssh tunnels is also helpful if you are on a network that you don’t trust and use websites that do not have strong cryptography. SSH traffic is encrypted and as such, the security risk will be less.

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If you do not want to add a certain file to your subversion repository, but it is already marked to be committed (by an already issued  svn add command) you can just type:

svn revert file.ext

to undo the add command.

If you remember to do it before the corresponding svn commit, doing this helps keeping the repository to a decent size. If you already commited the changes, you can remove it using svn delete (and an extra –force argument, if needed), but the space is wasted.