Browse Source

Dox updates

enhancement_3
Trevor Irons 8 years ago
parent
commit
2d36da5850
3 changed files with 94 additions and 73 deletions
  1. 20
    29
      Documentation/dox/compiling.dox
  2. 26
    11
      Documentation/dox/mem.dox
  3. 48
    33
      Documentation/dox/tutorial.dox

+ 20
- 29
Documentation/dox/compiling.dox View File

@@ -21,33 +21,32 @@ the prerequisites, but on many platforms this is easy.
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 - \ref Configuring
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 - \ref Building
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-\section Prerequisites Prerequisites
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-
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+\section OptionalPrerequisites Optional Prerequisites
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+- VTK - The Visualization ToolKit is a powerful data visualization framework. This is
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+  an optional dependency, but some functionality will be missing without it. Any
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+  version after 6.0 is fine. VTK is available under a BSD license from <http://vtk.org>
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+  Again--on Linux-- most package managers offer VTK. Compiling from source is not
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+  terribly difficult, but requires installing CMake as well. 
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+\note Some Lemma modules may impose additional (optional or mandatory) prerequisites, see the 
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+      module documentation.  
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-You will need to acquire the following free packages:
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-- SCons - SCons is a make replacement that is written in Python. It is easily
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-  configurable and directly controls the build process. It is not a Makefile
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-  intermediary like some similar applications. It is freely available at
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-  <http://scons.org>. On Linux, your package manager very likely provides this. On
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-  Windows it is slightly more complicated. But, hey, Windows is easy... right? That's why 
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-  you use it :)  The process is well documented on the SCons
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-  website. You might guess that we aren't huge Windows fans.
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-- Eigen3 - Eigen is a header-only linear algebra template library. It is made
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-  available under the Gnu Lesser Public License. It is available at
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-  <http://eigen.tuxfamily.org>. Please note that Lemma uses Version 3 of the Library.
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+\section Prerequisites Prerequisites
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+Lemma uses CMake to manage the build process (https://cmake.org). CMake is free software 
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+that is easy to install on about any operating system.  
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     \subsection Dependencies
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+    Hard dependencies are 
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+
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     The only dependencies are the Eigen linear algebra Library v3, a
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     C++ compiler and scons.
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-    (Currently a fortran compiler is needed too, see above)
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     The following compilers are fully supported and tested: gnu, mingw,
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     and intelc. Several routines are parallelised for shared memory platforms
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     using OpenMP. Any of the above compilers is able to be used with OpenMP.
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     Microsoft's Visual C++ compiler will likely be supported for stable
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-    releases, but is not actively tested. (Also the current FORTRAN compiler
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-    dependency limits this compiler as well.) Eigen extensively uses template
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+    releases, but is not actively tested. 
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+    Eigen extensively uses template
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     meta programming, the Borland compiler has been shown to be subpar at
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     optimizing this type of code and will likely never be supported actively.
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     A new compiler clang, is being developed and may prove to be promising as
@@ -63,19 +62,11 @@ You will need to acquire the following free packages:
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     be included in stable releases of Lemma.
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     Scons is a make replacement built on top of Python, and is also free.
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-\section OptionalPrerequisites Optional Prerequisites
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-- VTK - The Visualization ToolKit is a powerful data visualization framework. This is
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-  an optional dependency, but some functionality will be missing without it. Any
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-  version after 5.4 is fine. VTK is available under a BSD license from <http://vtk.org>
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-  Again-- on Linux-- most package managers offer VTK. Compiling from source is not
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-  terribly difficult, but requires installing CMake as well. Strangely (wink wink) this is 
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-  harder under Windows.
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-- Qt - Limited GUI support is provided leveraging the Qt framework. You will need to have 
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-  the development version of Qt 4 installed to use this. 
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-- Boost - Several classes use Boost. Lemma ships with a minimalist part of Boost and should compile 
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-	without it. However, if you are getting Boost errors while compiling, install the development version 
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-	 of boost. Note that Ubuntu ships with a very old Boost that has caused some issues. 
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-	Also, the Python wrapper requires boost.python and is not shipped with Lemma. 
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+- Eigen3 - Eigen is a header-only linear algebra template library. It is made
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+  available under the Gnu Lesser Public License. It is available at
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+  <http://eigen.tuxfamily.org>. Please note that Lemma uses Version 3 of the Library.
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+
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+
79 70
 
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 \section Downloading Acquiring the source
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 Lemma is currently available from svn checkout only. Note that while Lemma is still in Beta only

+ 26
- 11
Documentation/dox/mem.dox View File

@@ -14,31 +14,46 @@ namespace Lemma{
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 \section MemoryManagement Memory Management
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 \subsection Reference Reference counting and memory management
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-Lemma makes extensive use of reference counting. We do this for a variety of 
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-reasons. 
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-- It is not uncommon for multiple objects to have the same instantiations 
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-of an object as members.
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+
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+\note Previous versions of Lemma used an internal reference counting mechanism, what 
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+	is described below represents a significant change in the structure, philosophy, 
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+	and internals of Lemma. To a large extent this has been possible due to changes 
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+	in the C++ language specifications since C++-0x. These changes should improve the 
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+	readability of Lemma code, decrease errors, improve performance, and reduce code length.
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+	The C++-17 standard promises to close a remaining oddities in the Lemma API, discussed below. 
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+
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+Lemma relies heavily on smart pointer which utilize internal reference counting for several reasons: 
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+- It is not uncommon for multiple objects to have the same instantiations of an object as members.
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 - Making copies of each object is not a viable option because the objects may be large, and they must all update simultaneously.
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 - Without reference counting it is very easy to leave dangling pointers.
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 - It is much easier to write code, as local copies of objects can be deleted 
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 as soon as they are no longer used within that context. The memory will not be 
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 freed and the object persists as long as other objects still reference it.   
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-The base class for all Lemma objects is ReferenceCountedObject. 
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-The interface requires that all derived, non-abstract classes have <B>New</B> and <B>Delete</B> methods. So that objects may be created and destoyed with the 
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-following syntax.
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+The C++-0x standard introduced std::shared_ptr as a widely available, standard-compliant, high performance option to use 
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+in instances like this. The other smart pointer types specifically weak_ptr and unique_ptr are less handy in our application. As such, 
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+all Lemma classes expose a factory method returning a shared_ptr as the only publicly available means by which to construct objects. 
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+Internally, in cases where higher performance can be realized, manual memory management is employed.  
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+
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+The base class for all Lemma objects is LemmaObject. 
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+The interface requires that all derived, non-abstract classes have <B>NewSP</B> and <B>DeSerialize</B> methods. These methods are the only 
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+mechanisms by which you should be creating Lemma objects. 
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 \code 
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-DerivedClass* Object = DerivedClass::New();
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-Object->Delete();
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+std::shared_ptr< DerivedClass > Object = DerivedClass::NewSP();
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+// Or alternatively 
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+auto Object2 = DerivedClass::NewSP();
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 \endcode
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-\warning It is important to note that the default constructors and destructors are protected so the following code is <B>NOT</B> valid.
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+\warning It is important to note that the default constructors and destructors are inaccessible so the following code is <B>NOT</B> valid.
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 \code 
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 DerivedClass* Object = new DerivedClass;
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 delete Object; 
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 \endcode
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-The reasons for this will hopefully be clear soon.
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+Interestingly, the default constructors and destructors <B>are</B> public, however they are locked using a key struct 
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+<a href=http://stackoverflow.com/questions/8147027/how-do-i-call-stdmake-shared-on-a-class-with-only-protected-or-private-const/8147326#8147326> (link)</a>. 
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+The reason that this is necessary, is this arrangement allows for the use of std::make_shared to construct objects. The performance increase of this was 
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+chosen over the higher overhead associated with making the default methods protected. 
42 57
 
43 58
 Many Lemma classes have other Lemma classes as data members. Classes may
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 share these members, and depend on them being updated simultaneously. So 

+ 48
- 33
Documentation/dox/tutorial.dox View File

@@ -21,28 +21,52 @@ namespace Lemma{
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   | \ref EmSources "EM Sources"
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   </div>
23 23
 
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-Some basic information about Lemma to get you started. If you are familiar with
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-C++ and API's you can skip this page.
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-
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 \section C Why C++?
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-We get this a lot as most EM software seems to be written in fortran or Matlab. We
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-begin by discussing why we didn't choose certain languages/platforms.
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+We get this a lot as most EM software seems to be written in Fortran or Matlab. 
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+C++ has developed into a fast powerful language appropriate for scientific computing. 
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+The language is undeniably complex and can be intimidating (lots of bad C++ code is out there).
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+However, it is also possible to generate high performance, intuitive, flexible software using 
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+C++. In Lemma we take advantage of several recent changes to the language such that our public 
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+interface is simple to use, does not require manual memory management, and lets scientists focus on 
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+the problem at hand. The biggest hurdle for newcomers is often getting used to the object oriented 
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+approach we have taken. Rather than provide programs performing specific tasks Lemma exposes a 
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+flexible application programming interface (API) which can be though of as building blocks used 
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+to construct programs or projects.   
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+
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+\subsection API An API? What's that?
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+Lemma is not a program. It's an API, or an Application Programming Interface.
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+This offers a lot of advantages over traditional programs. 
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+- First, its flexible. Its easy to put together components to do exactly what 
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+  you want and nothing more. 
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+- Second, its extendible. If we have a class that does almost what you want, but is missing 
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+  something, you can just extend a class. 
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+- Third, it limits the amount of file IO you might need to do. We deviate from the Unix philosophy 
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+  of piping text streams between small applications, mainly because doing so is difficult on some 
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+  operating systems (I'm looking at you Windows), as well as cumbersome when used in graphical 
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+  user interfaces.
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+- Four, it enforces a consistent design and feel across the project. Once becoming familiar with 
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+  how Lemma objects are constructed, it becomes simple to use new building blocks. Think of the 
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+  objects as Lego's, since they are all constructed to work together, you can build anything. If 
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+  instead you have a mix of Lego, Lincoln Logs, and Tinker Toys you will be more more limited 
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+  in how you can use the pieces together.  
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-\subsection  Fortran Why not fortran?
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-We have  lots of reasons for choosing C++ over fortran, some of them better than others.
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-- We know it better, and we like it better. Too many hours debugging old 
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-  FORTRAN subroutines has left us jaded.
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+\subsection  Fortran Why not Fortran?
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+We have  lots of reasons for choosing C++ over Fortran, some of them better than others.
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+- We know C++ better, and we like it better. Too many hours debugging old 
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+  FORTRAN 77 subroutines has left us jaded.
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 - Easy integration with existing libraries. For example Lemma has built in 
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 support for VTK, an extremely powerful visualization package. We also include 
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-MATLAB file IO readers and an XML parser. Providing fortran wrappers for all 
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-of this would be a huge undertaking.
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+MATLAB file IO readers, an XML parser, and YAML class serialization. Providing Fortran 
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+wrappers for all of this would be a huge undertaking.
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 - Flexibility. Lemma is NOT a program, its an API that lets you build 
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- applications that fit your needs. This approach is a natural fit for object oriented
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+ applications that fit your needs. This approach is a natural fit for object oriented (OO)
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  programming and C++ is a much more natural choice for an OO project. 
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+ In spite of advances in the language, Fortran is still more geared towards procedural 
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+ programming paradigms (for better or worse). 
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 - Infinitely better interface. We leverage the Eigen 
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    <http://eigen.tuxfamily.org>  linear algebra package
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   to deliver expressive, fast code. Their benchmarks are right in line with 
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-  fast BLAS and LAPACK implimentations. If you honestly feel that 
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+  fast BLAS and LAPACK implementations. If you honestly feel that 
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 \code
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 DGEMM ( TRANSA, TRANSB, M, N, K, ALPHA, A, LDA, B, LDB, BETA, C, LDC )
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 \endcode  
@@ -50,35 +74,26 @@ DGEMM ( TRANSA, TRANSB, M, N, K, ALPHA, A, LDA, B, LDB, BETA, C, LDC )
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 \code
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   C = A*B.transpose(); 
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 \endcode 
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- you are living in denial. Check the benchmarks if you are still skeptical. 
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-- We know fortran 2003 has come a long way, but hey, so has C++. Give it a 
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+ you are living in denial. Check out the benchmarks if you are still sceptical
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+http://eigen.tuxfamily.org/index.php?title=Benchmark 
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+- We know Fortran has come a long way since FORTRAN 77, but hey, so has C++. Give it a 
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 chance.
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-\subsection Matlab Ok, so why not MATLAB?
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-First its closed source, second most large MATLAB programs suffer severe 
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-performance issues. Third, support for object-oriented programming is a joke. 
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-Finally, its also expensive and we don't think the graphics are all
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-that great.
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+\subsection MATLAB Why not MATLAB?
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+MATLAB is a closed source environment that is severely restrictive. The Lemma license is pro-business, 
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+we are happy if Lemma is used in commercial code and programs. MATLAB code is expensive and difficult to 
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+distribute in binary form. Also, the object oriented aspects of the MATLAB language feel a bit bolted on, and 
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+cumbersome to use.  We prefer to avoid MATLAB for these reasons. 
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63 88
 \subsection Python How about Python?
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-We like Python. While large 100% native Python applications are often very slow, it is easy to wrap fast C++ and Fortran routines around a Python interface. 
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-We actually plan on doing this in the future, and it is likely that at some 
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-point this may be the most common way to use Lemma. Lots of great visualization
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+We like Python. While large 100% native Python applications are often very slow, it is easy to wrap fast C++ and 
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+Fortran routines around a Python interface. We actually plan on doing this in the future, and it is likely that at 
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+some point this may be a common way to use Lemma. Lots of great visualization
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 solutions exist in Python (including VTK) and it is a great programming environment. The hard
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 part is that Eigen relies heavily on Expression templates that cannot be 
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 trivially wrapped into a python interface. So any python interface would have 
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 to be carefully constructed. We would welcome help in this department.
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 In the mean-time our API is elegant and easy to use.
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-
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-\section API An API? What's that?
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-Lemma is not a program. It's an API, or an Application Programming Interface.
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-This offers a lot of advantages over traditional programs. 
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-- First, its flexible. Its easy to put together components to do exactly what 
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-  you want and nothing more. 
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-- Second, its extendible. If we have a class that does almost what you want, you
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-  can just extend a class. 
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-- Third, it limits the amount of file IO you might need to do.
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-- Four, there are lots of other good reasons too. Just give it a try. 
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 */
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84 99
 /** @} */

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