Free to obtain software for linux

Netstation is a Linux distribution that enables you to convert standard PCs into full-featured diskless thin clients supporting all major connectivity protocols. The project can be booted from the network using Etherboot/PXE or from standard media like floppy/CD/hd/flash-disk etc. The configuration is centralized to simplify terminal management.
Terminal protocols supported
- X-Terminal XDM
- TightVNC
- SSH
- Telnet
- Rdesktop RDP
- Citrix ICA
- Tarantella
Boot methods
- DHCP/TFTP with Etherboot or PXE bootrom
- From floppy, hard disk, cdrom or DOC2000 using Syslinux
- From DOS using Loadlin
GUI modes
- Single client in fullscreen session
- Text session (Telnet or SSH)
- Multiple concurrent clients using local window manager
Other features
- Local printer support through network printer emualtion
- Network card, video card and mouse autodetection
- Dynamic ".nsp" package support (can be loaded at run time)
- Centralized configuration using TFTP to obtain config files"

FFT Spectra is a tool for the visualization of frequency spectra of an audio signal.

Among other things, it can be used to verify whether you are able to sing and whistle in tune or to tune your guitar.

Examples:

Didgeridoo

Didgeridoo is actually the reason, why i started writing this software. The theory of physics explains that when you blow into a cylindrical tube (such as didgeridoo, but PVC pipe works as well) and vibrate your lips, standing waves develop inside the tube.

At that end of the tube, where the air leaves, there is nearly atmospheric pressure and the standing wave has a node there. At the other end, where one blows the air in, the changes in pressure are maximal and the standing wave must have an antinode here.

The situation is depicted on the picture on the right: The horizontal axis represents a position along the tube and the vertical axis represents a maximal pressure variation from the constant atmospheric pressure. The black vertical line represents a zero variation. The left black point is the mouth-side enpoint of the tube. The pressure variation are maximal here. The black point on the right is the open side od the tube - the pressure is constant here.

This node/antinode restriction permits only standing waves with appropriate wavelength (e.g. frequency) to be developed. Other frequencies are forbidden. So, the red curve is a minimal (fundamental) frequency, which is present in the didgeridoo sound. (Corresponds to 70Hz on the picture bellow).

If we squeezed the red curve twice, i.e. made the frequency twice as high, on both end-points there would be an antinode and the node/antinode constrain would not be fulfilled. Really, we see that the peak at 140Hz bellow almost disappears. If we squeeze the curve a little bit more to obtain the green curve, the boundary condition is again met and the peak at 210Hz is clearly visible bellow. And so on.

dtoGe project is a java source generation tool that can ease the development of multi-tier systems by offering a reliable solution to obtain the data transfer objects out of the domain model objects without hand-writting additional code.

Using a simple set of javadoc tags, dtoGen™ provides the possibility to define the whole set of data transfer objects used by your system.

Harminv is a free program and C library for harmonic inversion: decomposing a time-series into a sum of sinusoids, including exponentially decaying sinusoids.
Harminv is based on the "filter diagonalization method" (FDM) of Mandelshtam & Taylor, which maps the harmonic inversion problem onto a small eigen-problem (size proportional to the number of sinusoids).
The FDM is often able to obtain much more robust and accurate solutions than alternative methods.
Enhancements:
- An inconsistent sign convention used for phase output was fixed.

Libuninum is a library for converting Unicode strings to numbers. Standard functions like strtoul and strtod do this for numbers written in the usual Western number system using the Indo-Arabic numerals, but they do not handle other number systems.
The main functions take as input a UTF-32 Unicode string and compute the corresponding unsigned integer. For example, they will convert the Chinese string ??????????? to the integer 594,321 and the Devanagari string ????? to the integer 78,492. Internal computation is done using arbitrary precision arithmetic, so there is no limit on the size of the integer that can be converted.
The value of the string is returned in one of two forms. One option is a string of ASCII characters containing the decimal representation of the integer using the Indo-Arabic digits. This option has the virtue of avoiding any possibility of overflow or truncation. The other option is to obtain the value as an unsigned long integer.
If you are going to do internal calculations, this is probably the most convenient option, but some numbers (in fact, infinitely many) will not fit into an unsigned long integer. The library guarantees that no overflow or truncation will occur; if the number will not fit, it sets an error flag and returns 0.
Enhancements:
- This version adds support for the more exotic forms of Roman numerals.
- Roman numeral compatibility characters are now accepted.

ost is a simple yet powerful tool providing mechanisms to automatically audit, maintain and backup systems customizations. ost is particularly well suited to environments where most systems are similarly configured, but will operate just as well if each system is unique.
ost uses at least one of the following two sets of input:
- the systems file catalog if it exists
- user defined "templates" to override the systems catalog
These allow ost to build a virtual image of what the local filesystem is supposed to look like. This image is then compared to the actual state of the local filesystem to obtain the following information about the system:
- List of intact files
- List of modified files
- List of missing files
- List of additional files

VETH is a daemon that creates a virtual ethernet card in Linux. This is done via the Universal TUN/ TAP Driver. It is useful to request more than one IP address via DHCP with a virtual ethernet card attached to an existing NIC.

Linux has an implementation that does the work, but partially. Sometimes, this emulation doesnt work as expected. Because of this, I wrote VETH, to be helpful in this situations.

For example, if you want to have more than one IP address obtained via DHCP probably you know thats impossible. With VETH you can attach a virtual ethernet into an existent NIC card, and the run dhclient in it to obtain a new IP.

Perhaps you are saying "hey, man, dont mess with me, I can do that with aliasing. With an ifconfig eth0:1 I have a new ethernet". OK, perhaps, perhaps...

It isnt 100% true. Look at this scenario:

You have a DSL modem working as a bridge. You have a firewall with exactly 2 NICs, no more. One of these NICs is crossover-connected to your modem, and another is in your internal subnet.

GtkSysinfo project is a perl-Gtk2 software for Linux which makes it possible to obtain a maximum of information about the system such as temperature(with lm_sensors) , CPU frequency, hardware(with PciUtils) , network , ACPI ...