Calculus in 20 minutes

This guy is freakin amazing!

some older Grass GIS tutorial and ebook

I found two older documents about Grass GIS. Both seems quite valuable.
Legal one - Grass5 tutorial in homepage here
Illegal one in rapidshare - not mine, just found it - A Grass GIS Approach, 2nd edition


What could be done with ultracapacitors or eletric double-layer capacitors?
from wiki:
They have applications as energy-storage devices used in vehicles, and for smaller applications like home solar energy systems where extremely fast charging is a valuable feature.

Pretty neat video about unusual ultracapacitor use


Outsim Synthmaker v1.1.1.

It is very easy to build your own custom VSTi`s with this soft. It cames with good manual/tutorial where you can build a sample synth and also it has good wiki site.

I made sample synth and I was playing around it, and here I`ll build something more simple.

In the beginning I`m choosing midi input, and as I dont have any but keyboard, then I use it.

Next I`m adding two more modules - ASIO output (faster than usual ones, download here -> asio homepage) and midiToPoly. I enable PC Keyboard (it becomes red) and ASIO output (becomes blue) and connect Midi In to MidiToPoly.
I`m going to edit MidiToPoly module becouse I`ll use it as simple as I can. Double click on it and woala

There is a selector which selects frequency output type between normalized and usual one. Smaller red box shows playing classic note A and related frequencies. Larger red box shows primitives which I will delete, so I`ll directly connect Portamento frequency output to module output.
Now it becomes clear and simple.
And now - why did I delete that stuff? I want to add the sine wave oscilator primitive. And it needs normalized frequency. If it is so, then why should I use another converter to convert frequency to normalized or use that selector?
Almost finished - I`m adding stereo clip, which cuts mono values below 1 (because if it is above 1 it`s getting distorted)
And last modification - phase inverter using code. I`ll take one of StereoClip output and invert its phase using code textbox. Code textbox you can find under tab named "Other" or just search for "code"
And here it is. input has been taken and output is phase inverted source.


Python and Qt4 Designer

On my windows machine I had a mouse related problem. Using VLC or QGIS I was unable to work with mouse - buttons didn`t respond on mouse clicks, yet still I was able to use keyboard shortcuts in VLC, but working in QGIS was completely unusable. I started look around where`s problem and I tried uninstall everything which I dont need and i`m not using and will not use. There it was - Microsoft Visual C++ and other related stuff. Uninstalling it, VLC and QGIS mouse clicks started to work normally.

The fact is, both - QGIS and VLC are Qt based and compiled programs, and Qt was somehow conflicting with Microsoft products.

I started to look around, what exactly is Qt.. and i found that it`s freeware framework, which is compatible with some programming languages, e.g. C++, Python.

I tried to search some tutorials, and the best what i found is in youtube.

Take a look.


QGIS 1.6.0. released

New vesion of Quantum GIS, 1.6.0-Capiapo has been released last month, 17.11.2010
I didn`t try previous one, 1.5.0, but version 1.4.0 had some bugs, which seems to be corrected in the last one.
Adding WMS layers. There were some errors chosing more than one layer from server, but now it is repaired.
Ftools and defining Shapefile`s projection. Previously I got some python related errors, but from version 1.5.0 it works flawlesly.

Digitizing vectors gave headaches. If I have to digitize large area in large scale (or small scale.. which is more correctly?) - close enough, then i have to move base layer - it doesnt fit in screen. Moving layer is elementary - with mouse. But if I am digitizing in that time, how can it is possible to move layer? Dont have an extra mouse for layers... still i have shortcuts - keyboard arrows. This mouse thing WAS NOT working in v.1.5.0, so it IS working in v.1.6.0

I`m very proud that Grass support is almost fully implemented in QGIS. This gives huge additional boost for windows users. There`s no need to manually add qgis grass plugins, from v.1.5.0 it is included in one bundle. Install, next,next,finish and you get full qgis with grass support.


combining two statistical parameters to get best suitability

R square value (coefficient of determinant) and root mean square error (rmse). These are typical parameters which shows, how two arrays are dependent from each other.

R square value shows tedency and is very easy calculated in MS Excel using command "=correl(array1[Ax:Ax+n];array2[Bx:Bx+n])^2" and it is calculated by formula
Equation 5. Equation. Coefficient of Determination. Uppercase R squared equals 1 minus summation under script lowercase i belongs to uppercase I open parentheses uppercase Y subscript lowercase i minus uppercase Y hat subscript lowercase i close parentheses raised to the second power divided by summation under script lowercase i belongs to uppercase I open parentheses uppercase Y subscript lowercase i minus uppercase Y bar close parentheses raised to the second power.

Root mean square error shows difference between two given data arrays. It is calculated by taking each data pair and getting their difference, and finally RMSE is equivalent to standart deviation of all these differences. Not too complicated as it seems.

R-squared is between 0 and 1. Usually RMSE is absolute and something positive (newertheless differences between data pairs still could be negative, but standart deviation always will be positive, even calculated from negative data - it is absolute deviation). But it is possible to get RMSE value relative, knowing each data array minimum and maximum values. Relative RMSE (RRMSE) = RMSE/maxx-minn

Now, both parameters are between 0 and 1.
Best suitability (BS) would be if R-squared = 1 (ascending) and RRMSE = 0 (descending)

Weights. Sometimes it is useful to give different weights to each of these statistical parameters. It`s simple - just multiply each coefficient with its weight.
I want that RMSE is twice hevier parameter than R^2.
BS = R^2 - RMSE*2

Sometimes it is useful to add some constante
BS = R^2 - RMSE + Const
but very rare.


Historical maps

Long time no see.
There`re few things waiting for writing them here.
But for now - some interesting historical Near East maps
Kish hegemony (2800-2500 BC)
Ebla hegemony (2500-2250 BC)
Lagash Hegemony (2454-2342 BC)
Uruk Lugalzagesi (2342-2318 BC)
Uruk Utukhengal (2123-2113 BC)
Ur empire (2112-2004 BC)
Isin empire (2017-1925 BC)
Babylon-Isin empire (1125-1103 BC)
Eshnunna empire (1830-1815 BC)
NeoBabylon empire (626-539 BC)
Akkad empire (2334-2154 BC)
Assirian empire
Antique (1813-1781 BC)
Middle (1365-1076 BC)
Late (935-609 BC)
Paleobabylonian (1792-1640 BC)
Karduniash empire (1570-1155 BC)
Mitanni empire (1500-1350 BC)
Damascus empire (842-797 BC)
Seleucid empire (305 - 63 BC)
Palmyr empire (260-272 AD)
Umayyad empire (661-750 AD)
Abbasid empire (750-945 AD)
Zengida empire (1127-1175 AD)
Jalayarid empire (1336-1432 AD)

Take a look Here