.. title: PAR Class 17, Thurs 2021-03-25
.. slug: class17
.. date: 2021-03-25
.. tags: class
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Student talks
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#. Connor. cloud-based/docker-base parallel computing.

#. Isaac. Aerospace.

#. Jack. Nvidia's autonomous machines.

   
Several forms of C++ functions
------------------------------

#. Traditional top level function

     auto add(int a, int b) { return a+b;}

   You can pass this to a function.  This really passes a pointer to the function.  It doesn't optimize across the call.
   
#. Overload **operator()** in a new class

   Each different variable of the class is a different function.  The function can use the variable's value.   This is a closure.

   This is local to the containing block.

   This form optimizes well.
   
#. Lambda, or anon function.

     auto add = [](int a, int b) { return a+b;};

   This is local to the containing block.
   
   This form optimizes well.

#. Placeholder notation.

   As an argument in, e.g., transform, you can do this:

      transform(..., _1+_2);

   This is nice and short.
   
   As this is implemented by overloading the operators, the
   syntax of the expression is limited to what was overloaded.

   
Thrust
------

#. Thrust is an API that looks like STL. Its backend can be GPU-CUDA,
   OpenMP, TBB, or sequential host-based code.


#. Functional-programming philosophy.

#. Easier programming, once you get used to it.

#. Code is efficient.

#. Uses some unusual C++ techniques, like overloading **operator()**.

#. Since the Stanford slides were created, Thrust has adopted
   unified addressing, so that pointers know whether they are
   host or device.


   
#. `Stanford's parallel course notes <../files/stanford/>`_.

  We'll start lecture 8, which has a lot of content.  Today we did up thru slide 24.