Imagine you are new user of linux or (even windows )and you want to write a program in C++ and you need to use Lapack++.how will you do .
please step by step from lapack installation until how to call the fuctions .and if any pictures it will be greatful .

You can usually install any needed softwarer on Linux through your distributions package manager. Look for a package named "lapack++" or "lapack" and install that.

You should then be able to use the classes provided by lapack like you would a normal C++ class. ( #include , make calls using class::function() )

It's funny that you ask this here.

KDE has it's own linear algebra library called "eigen2" which is no no way based on BLAS or LAPACK. So I'd say there are much better fitting forums than the KDE forum. But I think also these forums will be of more use for you if you have a specific problem. On the Lapack++ homepage you'll find an installation guide (if you want to install from source), a user manual (with code examples) and a reference guide. On the Lapack++ sourceforge page there's also an online documentation, also with installation instructions and a section "Quickstart".

I hope this helps you a bit to get your problems solved and LAPACK++ up and running. Of course you can reply here if you have any further questions, but it's been years since I used (original Fortran) LAPACK routines, so, as said above, I think there are better forums for LAPACK++ related questions, as this forum is in no way LAPACK related.

If your question is even more general in the sense that you want to know how to set up a compiler and/or an IDE: I'm sorry, I think this is way beyond the scope of a thread in any user forum. But there are a lot of websites and good books that teach you the basics of C++ programming. As tastes are very different on what site or book is the best, just ask google, read a bit, stay there if you like it, or try the next