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From: James_Rogers <jrogers@velveeta.apdev.cs.mci.com>
Subject: Re: What's the best language to start with? [was: Re: Should I learn
 C or Pascal?]
Date: 1996/08/15
Message-ID: <32134490.41C6@velveeta.apdev.cs.mci.com>#1/1
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references: <4uaqqg$203@mulga.cs.mu.OZ.AU>
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 <4ug10l$14p@solutions.solon.com>
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Date: 1996-08-15T00:00:00+00:00
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Peter Seebach wrote:
> Tim Behrendsen <tim@airshields.com> wrote:
>>>>int a[50000],b[50000],c[50000],d[50000],e[50000];

>>>>void test1()
>>>>{
>>>>  int i,j;
>>>>  for (j=0;j<10;++j){
>>>>    for (i=0;i<50000;++i){
>>>>      ++a[i];++b[i];++c[i];++d[i];++e[i];
>>>>    }
>>>>  }
>>>>}

>>>>void test2()
>>>>{
>>>>  int i,j;
>>>>  for (j=0;j<10;++j){
>>>>    for (i=0;i<50000;++i) ++a[i];
>>>>    for (i=0;i<50000;++i) ++b[i];
>>>>    for (i=0;i<50000;++i) ++c[i];
>>>>    for (i=0;i<50000;++i) ++d[i];
>>>>    for (i=0;i<50000;++i) ++e[i];
>>>>  }
>>>>}

This example also behaves differently than predicted by
Mr Behrendsen when implemented in Ada 95 using the GNAT
compiler on a SPARC 20.

I translated the above functions into Ada as follows:
   procedure test1 is
   begin
      for J in 1..10 loop
         for I in index_type loop
            a(I) := a(I) + 1;
            b(I) := b(I) + 1;
            c(I) := c(I) + 1;
            d(I) := d(I) + 1;
            e(I) := e(I) + 1;
         end loop;
      end loop;
  end test1;
  
  procedure test2 is
  begin
     for J in 1..10 loop
        for I in index_type loop
           a(I) := a(I) + 1;
        end loop;
        for I in index_type loop
           b(I) := b(I) + 1;
        end loop;
        for I in index_type loop
           c(I) := c(I) + 1;
        end loop;
        for I in index_type loop
           d(I) := d(I) + 1;
        end loop;
        for I in index_type loop
           e(I) := e(I) + 1;
        end loop;
     end loop;
  end test2;

Each of the above loops was run 10 times.  The
timings are given below.

The resulting timings with no optimization are:
Test1 execution time:          12.2815
Test2 execution time:          16.0227

With full optimization and inlining of procedures the 
results are:
Test1 execution time:           4.6333
Test2 execution time:           5.2464

Using Ada the performance is quite comperable to Mr Seebach's
C results using gcc.  The Ada results also do not support Mr
Behrendsen's position.

-- 
Jim Rogers
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