AW: [scilab-Users] Why an interpreter?

[Harald Galda, Dr. Eng. (J)]

Hello everyone.

Even though I am no expert in the field of compilers and interpreters I would 
like to share some thoughts and observations.

Matlab does have a compiler. The compiler is a separate toolbox  and more 
expensive than Matlab itself or any other toolbox. However, a compiled program 
does not run faster than the interpreted program run in Matlab. Maybe a compiled 
program is a little faster if Matlab is not installed and therefore does not 
occupy any resources such as RAM and disk space. 


There is another interesting effect: a function called for the first time during 
a session runs much slower than during all consecutive runs. So it seems that 
the interpreter translates the source code into some intermediate code. A 
function that runs on the Matlab level can access the resources of the basis 
software such as work space and it can display outputs on the basis software 
console. This would be completely impossible if the function were compiled as a 
stand alone program. Running selected parts of a script or function also 
requires interpreted code.

It is possible to call compiled programs written in C from Scilab, Matlab or 
Mathematica. However, these programs usually must exchange data with the basis 
software or functions calling these programs. It takes time to copy huge amounts 
of data or to write them to and read them from disk. Therefore, it is not 
desirable to compile each and any function as a separate program. A compiler is 
necessary for stand alone software, but not for functions run inside numerical 
software.

Stand alone programs are often written in C or C++. There are a lot of libraries 
written in these languages. Moreover, there are some wide spread development 
environments for C and C++. Embedded Matlab, Simulink and XCos can generate C 
code. Maybe there will be something like embedded Scilab to create C code in the 
future. Therefore, it is possible to combine the advantages of interpreted 
numerical software and fast C programs.

For these reasons, I conclude that numerical software will continue to run 
interpreted code for the time being.

Best regards
Harald Galda, Dr. Eng. (J)





________________________________
Von: Pedro Ledoux <p_ledoux at yahoo.com.br>
An: users at lists.scilab.org
Gesendet: Samstag, den 2. Oktober 2010, 4:01:50 Uhr
Betreff: [scilab-Users] Why an interpreter?


Hello everyone.

Scilab, Matlab, Octave and others softwares of this kind uses an interpreter not 
a compiler. Is there any specific rason to do it? I don't know deeply the 
technical details about interpreters and compilers but i've become curious about 
it. In long interative process a compiled code runs much more faster because in 
a interpreter to each interation the language commands should be converted to 
machine language and in a compiled one it happens only one time when the object 
code is generated. Was told me that in a interpreter debug is more easy. So why 
those everyoments chose do numerical process by an interpreted language?

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