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VANDALISM
They are terms of an algebraic expression
a number
http://en.wikipedia.org/wiki/Pythagorean_theoremThe theorem can be written as an equation:a2 + b2 = c2where c represents the length of the hypotenuse, and a and b represent the lengths of the other two sides.1. side squared plus 2. side squared is equal to hypotenuse squared.If you have c= 10cmb=4cmthen you can calculate the a using this theorem.c2 = a2 + b2a2 = c2 - b2a = √a2( a= √c2-b2 )easy ;)
Frequency converters are common in radio transmitters and receivers, also in any[analog] device that has to combine many phone-calls onto one cable, or separatethem into individuals on the other end of the cable.When the frequency of a signal needs to be converted, the 'machine' that does ithas another signal source inside, and the two signals are fed together to a 'mixer'.In principle, the 'mixer' can be any nonlinear device, because those always createnew frequencies. Non-linear things include diodes, and amplifiers that are beingpushed to the max. (The fuzzy 'audio distortion' you hear when you crank youramp too high is actually the new frequencies that are created when the audiofrequencies mix on their way through it.)Here's the idea: Let's say the frequency you have is 'A', and the frequency of thesource inside the machine is 'B'. Feed these two signals together into a non-lineardevice and, believe it or not, here are the frequencies that come out of it:ABA+BA-B2A+B2A-B2A+2B2A-2B3A+B3A-B3A+2B3A-2B3A+3B3A-3B..etc.Each and every one of these 'mix products' is a copy of your signal 'A' ... carryingthe same modulation (information) with it, at a different frequency.Look back toward the top of the list, where you see "A+B" and "A-B" ... the sumand difference of your frequency and the one generated inside the 'machine'.These are typically the strongest products that come out of the mixer, and they'rethe ones that are most often used. The output of the mixer is simply 'filtered' toget rid of all the unwanted mix products.All you have to do is adjust the internal signal 'B' to whatever frequency it needsto be, in order to place either the sum, A+B, or the difference, A-B, at the frequencywhere you want your copy of 'A' to appear.The most familiar example of this process is AM radio:-- 'A' is the music or voice signal that comes from the microphone.-- 'B' is the carrier frequency, generated inside the transmitter.-- 'A+B' is a copy of the music/voice signal, near the carrier frequency.This 'copy' is what gets broadcast, and what comes into your radio ...along with many other signals at other frequencies.-- You move the pointer on your radio dial to 'B'. In principle, that sets thefrequency of a source inside your radio to 'B'. Then that internal signal goesto the mixer in the radio, along with all the stuff coming in from the antenna.Remember that one of the signals from the antenna is at frequency A+B.-- One of the frequencies coming out of the mixer is the difference of these two:(A+B) - B-- That's just 'A' ... the music and voice signal, which you only have to run to yourspeaker or earphones, and the job is done.============================(A purist reading this will object to my simplification on the receiving end,and will want to jump in and add the descriptions of the superheterodynesystem, and the conversion to IF before the detector. Please don't. Thequestion has been answered and an example given in principle. Correct itif it's wrong, but we'll lose people if you 'improve' it.)
Follow the instructions provided by the official Boost website (see related links below):InstallationTo install Boost.Build from an official release or a nightly build, as available on the official web site, follow these steps: Unpack the release. On the command line, go to the root of the unpacked tree.Run either .\bootstrap.bat (on Windows), or ./bootstrap.sh (on other operating systems).Run ./b2 install --prefix=PREFIX where PREFIX is a directory where you want Boost.Build to be installed.Optionally, add PREFIX/bin to your PATH environment variable.If you are not using a Boost.Build package, but rather the version bundled with the Boost C++ Libraries, the above commands should be run in the tools/build/v2 directory.Now that Boost.Build is installed, you can try some of the examples. Copy PREFIX/share/boost-build/examples/hello to a different directory, then change to that directory and run: PREFIX/bin/b2A simple executable should be built.
there are 4 types 1. B2B 2.B2C 3. C2B 4. C2C