30% difference in speedof C# vs C++ for math?

[Rich]

I was considering C# for developing a scientific application, but I have
noticed a ~30% difference between VC++ .NET and C# on the same machine,
under identical conditions:

double a = 0,b = 0, c = 0, d = 0, e = 0;
for(int n = 0; n != 6000000; n++)
{
a = n % 5 *2 / 3 - 4 + 6 / 3 - n + n * 2;
b = n * 2.3 - 1 *2 / 3 - 4 + 6 / 3 - n + n * 2;
c = n * 3 / 3.5 *2 / 3 - 4 + 6 / 3 - n + n * 2;
d = n + 1 * 2 *2 / 3 - 4 + 6 / 3 - n + n * 2;
e = n / 2 *2 / 3 - 4 + 6 / 3 - n + n * 2;
}

It takes 2300ms in VB.NET, 1000ms in C# but only 700ms in VC++

Does this sound right?

Thanks.
Richard

[realfun]

did you build in release version?
did you open the optimizing parameter in the building process?
is the VC++ code native or managed?

all of these will affect the performance.

[Rich]

<re*****@gmail. com> wrote in message
news:11******** **************@ f14g2000cwb.goo glegroups.com.. .

did you build in release version?
did you open the optimizing parameter in the building process?
is the VC++ code native or managed?

all of these will affect the performance.

1. Both were run in Release mode (C# and VC++).
2. The VC++ program was optimized for speed. I could not find a similar
option for C#
3. The VC++ code is native.

Is there an option to maximize speed in a compiled C# application?

Richard

[Johann Blake]

Richard,

If you need that kind of speed, buy a math component (and one
particular to your type of application) and use C# to develop the GUI
and business logic. That makes far more sense than writing everything
in C++.

Best Regards
Johann Blake

[Rich]

"Johann Blake" <jo*********@ya hoo.com> wrote in message
news:11******** **************@ g43g2000cwa.goo glegroups.com.. .

Richard,

If you need that kind of speed, buy a math component (and one
particular to your type of application) and use C# to develop the GUI
and business logic. That makes far more sense than writing everything
in C++.

Best Regards
Johann Blake

C++ is OK for me, I have been using it for 15 years. But I thought I would
gain some type of advantage by switching to C#

Well apparently not, because I'm not sure if I would want to do something
crazy like:

ClumsyThirdPart yMathLibrary clumsy = new ClumsyThirdPart yMathLibrary();
double a = 0,b = 0, c = 0, d = 0, e = 0;
for(int n = 0; n != 6000000; n++)
{
a =
clumsy.Multply( clumsy.Add(clum sy.Subtract(clu msy.Divide(clum sy.Add(clumsy.S u
btract(clumsy.D ivide(clumsy.Mu ltiply(clumsy.M od(n, 5) * 2), 3) 4), 6), 3),
n), n), 2);
b = n * 2.3 - 1 *2 / 3 - 4 + 6 / 3 - n + n * 2;
c = n * 3 / 3.5 *2 / 3 - 4 + 6 / 3 - n + n * 2;
d = n + 1 * 2 *2 / 3 - 4 + 6 / 3 - n + n * 2;
e = n / 2 *2 / 3 - 4 + 6 / 3 - n + n * 2;
}

I couldn't even finish the first line. I've got just 11,000 more to go.
C# should be faster. One shouldn't have to resort to clumsy stuff like that.

Richard

[Johann Blake]

Richard,

I should have made my point much clearer. You don't use a third party
math library to do basic math. The library should contain the math
functions pertinent to what you want to accomplish. For example, if you
need to run a DSP FFT algorithm on an analog signal, you use a DSP
library with a FFT function.

Since you already know C++, write these functions yourself in C++ and
call them from C#. That is what I am doing at the moment. All my "math"
stuff is in C++ but the actual GUI and business logic is C#.

Developing GUI and business logic in C# makes far more sense and has
far more advantageous than doing it in C++.

Johann

[Christoph Nahr]

On Wed, 3 Aug 2005 22:19:41 -0700, "Rich" <[e-mail] d> wrote:

I couldn't even finish the first line. I've got just 11,000 more to go.
C# should be faster. One shouldn't have to resort to clumsy stuff like that.

Who said it "should" be faster? Santa Claus?

Different languages are better at different things. C# is great at
things like speed of development, clarity of code, runtime linking,
memory management. C++ is great at things like hardware access,
porting to many different systems, and raw speed.

Your experience is the same as mine, by the way. In numerical code,
C# is only 50-80% the speed of C++. That's how it is, for now. But
(Visual) C++ is a fairly stable language that has had many years of
gradual optimizer improvements while C# and .NET are still getting a
ton of new features with each release (example: generics in 2.0,
embedded database queries planned for 3.0). Once the Microsoft teams
start focusing on the optimizer numerical code might improve, too.
--
http://www.kynosarges.de

[Octavio Hernandez]

Rich,

a) Your code does not really test floating point arithmetic. Since variable
n and all the constants used are integers, you're only doing integer
arithmetic there...

b) If you're comfortable with C++, maybe you should consider using Visual
C++ 2005. It offers most of the productivity-enhancement tools that there
are in VS 2005 for C#, and it's the only language that allows you to mix
native and managed code. This will allow you to recompile your
math-intensive code as native, if the tests show that managed code is
significantly slower than native, with minimum effort.

Regards - Octavio

"Rich" <[e-mail] d> escribió en el mensaje
news:evdIe.5506 1$4o.50065@fed1 read06...

I was considering C# for developing a scientific application, but I have
noticed a ~30% difference between VC++ .NET and C# on the same machine,
under identical conditions:

double a = 0,b = 0, c = 0, d = 0, e = 0;
for(int n = 0; n != 6000000; n++)
{
a = n % 5 *2 / 3 - 4 + 6 / 3 - n + n * 2;
b = n * 2.3 - 1 *2 / 3 - 4 + 6 / 3 - n + n * 2;
c = n * 3 / 3.5 *2 / 3 - 4 + 6 / 3 - n + n * 2;
d = n + 1 * 2 *2 / 3 - 4 + 6 / 3 - n + n * 2;
e = n / 2 *2 / 3 - 4 + 6 / 3 - n + n * 2;
}

It takes 2300ms in VB.NET, 1000ms in C# but only 700ms in VC++

Does this sound right?

Thanks.
Richard

[Willy Denoyette [MVP]]

I can't believe there is such a huge difference between VB and C#, there
must be something wrong here.
Mind to post the whole code?

Willy.
"Rich" <[e-mail] d> wrote in message
news:evdIe.5506 1$4o.50065@fed1 read06...

I was considering C# for developing a scientific application, but I have
noticed a ~30% difference between VC++ .NET and C# on the same machine,
under identical conditions:

double a = 0,b = 0, c = 0, d = 0, e = 0;
for(int n = 0; n != 6000000; n++)
{
a = n % 5 *2 / 3 - 4 + 6 / 3 - n + n * 2;
b = n * 2.3 - 1 *2 / 3 - 4 + 6 / 3 - n + n * 2;
c = n * 3 / 3.5 *2 / 3 - 4 + 6 / 3 - n + n * 2;
d = n + 1 * 2 *2 / 3 - 4 + 6 / 3 - n + n * 2;
e = n / 2 *2 / 3 - 4 + 6 / 3 - n + n * 2;
}

It takes 2300ms in VB.NET, 1000ms in C# but only 700ms in VC++

Does this sound right?

Thanks.
Richard

[Mattias Sjögren]

I can't believe there is such a huge difference between VB and C#, there
must be something wrong here.
Mind to post the whole code?

I'm guessing that the VB code uses the / operator which performs
implicit floating point division (as opposed to \), whereas the C#
code just does integer math like Octavio said. That would account for
at least some of the difference.

Mattias

--
Mattias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
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