Hi there,
I need to make a poisson distribution function that uses:
double Math.Exp(double d)
The d argument is a negative number in my case. When d becomes bigger and
bigger, the result loses precision and is finally 0 (when d reaches 650)
because it is too small to fit in a double. In my case, d can become -10000,
so I need to have a greater precision number and Exp function.
I've looked at decimal, but it cannot contain as small a number as double
(just try to put a small double in a decimal and the decimal will be 0).
Furthermore, there is no Math.Exp overload that takes decimals.
Any suggestions anyone?
Thanks,
Michel ms*@virtualsciences.nl 8 1793
"Michel" <ms*@virtualsciences.nl> wrote in message
news:bp**********@reader11.wxs.nl... Any suggestions anyone?
Maybe a good opportunity to try a Fortran compiler for .NET, I've found
some: http://www.salfordsoftware.co.uk/com...5/dotnet.shtml http://www.lahey.com/lf70/lfnet.htm
These compilers will probably handle numeric types with a higher precision
or provide a better implementation of Math functions. You can write a
component in Fortran.NET that does the job but you must remember that the
interface with this component must only use CLS compliant types,
System.Double or System.Decimal in your case.
Given the size of the value you're passing, I don't think there's any type
that would work well. I can think of a few things to try:
1) Find a library that supports larger exponents. There may be some on this
page - http://www.oonumerics.org/oon/ - but my guess is that you won't find
a C# one. You might be able to find a free Java one and either
hand-translate or run the Java Language Conversion Assistant on it (assuming
the license allows that).
2) Modify your calculation so that you don't need to compute the entire
value all at once. If, for example, you are going to multiply this by
something that is pretty big, you can factor apart the calculation, apply
Math.Exp(-10) 4 times to get the equivalent of Math.Exp(-10000)
Hope that helps.
--
Eric Gunnerson
Visit the C# product team at http://www.csharp.net
Eric's blog is at http://blogs.gotdotnet.com/ericgu/
This posting is provided "AS IS" with no warranties, and confers no rights.
"Michel" <ms*@virtualsciences.nl> wrote in message
news:bp**********@reader11.wxs.nl... Hi there,
I need to make a poisson distribution function that uses:
double Math.Exp(double d)
The d argument is a negative number in my case. When d becomes bigger and bigger, the result loses precision and is finally 0 (when d reaches 650) because it is too small to fit in a double. In my case, d can
become -10000, so I need to have a greater precision number and Exp function.
I've looked at decimal, but it cannot contain as small a number as double (just try to put a small double in a decimal and the decimal will be 0). Furthermore, there is no Math.Exp overload that takes decimals.
Any suggestions anyone? Thanks, Michel ms*@virtualsciences.nl
Hi Eric,
I'd like to try breaking the calculation up.
How do I get from Math.Exp(-10) back to Math.Exp(-10000)?
I've done some testing....
Math.Exp(-4) = Math.Exp(-2) * Math.Exp(-2)
However, this doesn't apply to e.g. 100:
Math.Exp(-100) != Math.Exp(-10) * Math.Exp(-10).
Also, my input is not as "nice" as 10000, it'll be more like 1234,56.
Thanks,
Michel
"Eric Gunnerson [MS]" <er****@online.microsoft.com> wrote in message
news:%2****************@TK2MSFTNGP12.phx.gbl... Given the size of the value you're passing, I don't think there's any type that would work well. I can think of a few things to try:
1) Find a library that supports larger exponents. There may be some on
this page - http://www.oonumerics.org/oon/ - but my guess is that you won't
find a C# one. You might be able to find a free Java one and either hand-translate or run the Java Language Conversion Assistant on it
(assuming the license allows that). 2) Modify your calculation so that you don't need to compute the entire value all at once. If, for example, you are going to multiply this by something that is pretty big, you can factor apart the calculation, apply Math.Exp(-10) 4 times to get the equivalent of Math.Exp(-10000)
Hope that helps.
-- Eric Gunnerson
Visit the C# product team at http://www.csharp.net Eric's blog is at http://blogs.gotdotnet.com/ericgu/
This posting is provided "AS IS" with no warranties, and confers no
rights. "Michel" <ms*@virtualsciences.nl> wrote in message news:bp**********@reader11.wxs.nl... Hi there,
I need to make a poisson distribution function that uses:
double Math.Exp(double d)
The d argument is a negative number in my case. When d becomes bigger
and bigger, the result loses precision and is finally 0 (when d reaches 650) because it is too small to fit in a double. In my case, d can become -10000, so I need to have a greater precision number and Exp function.
I've looked at decimal, but it cannot contain as small a number as
double (just try to put a small double in a decimal and the decimal will be 0). Furthermore, there is no Math.Exp overload that takes decimals.
Any suggestions anyone? Thanks, Michel ms*@virtualsciences.nl
"Michel" <ms*@virtualsciences.nl> wrote in message news:<bp**********@reader11.wxs.nl>... Hi there,
I need to make a poisson distribution function that uses:
double Math.Exp(double d)
The d argument is a negative number in my case. When d becomes bigger and bigger, the result loses precision and is finally 0 (when d reaches 650) because it is too small to fit in a double. In my case, d can become -10000, so I need to have a greater precision number and Exp function.
I've looked at decimal, but it cannot contain as small a number as double (just try to put a small double in a decimal and the decimal will be 0). Furthermore, there is no Math.Exp overload that takes decimals.
Any suggestions anyone? Thanks, Michel ms*@virtualsciences.nl
If you look at http://groups.google.com/gr*********...ing.google.com
you'll see a discussion on how to calculate probabilities associated
with the Poisson distribution.
Ian Smith
Michel,
exp(-100) == exp(-10) * exp(-10)
in mathematical terms. It's not equal in the computer, however, because the
floating-point representation is inexact.
I'm assuming that you would multiplying this the result of exp(-10000) by a
large positive number. If not, then your result might be outside the range
of double anyway.
I hope that helps. If you have more questions, please give us some more
information on what you're trying to do and what algorithm you're using.
--
Eric Gunnerson
Visit the C# product team at http://www.csharp.net
Eric's blog is at http://blogs.gotdotnet.com/ericgu/
This posting is provided "AS IS" with no warranties, and confers no rights.
"Michel" <ms*@virtualsciences.nl> wrote in message
news:bq**********@reader11.wxs.nl... Hi Eric,
I'd like to try breaking the calculation up. How do I get from Math.Exp(-10) back to Math.Exp(-10000)? I've done some testing.... Math.Exp(-4) = Math.Exp(-2) * Math.Exp(-2)
However, this doesn't apply to e.g. 100: Math.Exp(-100) != Math.Exp(-10) * Math.Exp(-10).
Also, my input is not as "nice" as 10000, it'll be more like 1234,56.
Thanks, Michel
"Eric Gunnerson [MS]" <er****@online.microsoft.com> wrote in message news:%2****************@TK2MSFTNGP12.phx.gbl... Given the size of the value you're passing, I don't think there's any
type that would work well. I can think of a few things to try:
1) Find a library that supports larger exponents. There may be some on this page - http://www.oonumerics.org/oon/ - but my guess is that you won't find a C# one. You might be able to find a free Java one and either hand-translate or run the Java Language Conversion Assistant on it (assuming the license allows that). 2) Modify your calculation so that you don't need to compute the entire value all at once. If, for example, you are going to multiply this by something that is pretty big, you can factor apart the calculation, appl
y Math.Exp(-10) 4 times to get the equivalent of Math.Exp(-10000)
Hope that helps.
-- Eric Gunnerson
Visit the C# product team at http://www.csharp.net Eric's blog is at http://blogs.gotdotnet.com/ericgu/
This posting is provided "AS IS" with no warranties, and confers no rights. "Michel" <ms*@virtualsciences.nl> wrote in message news:bp**********@reader11.wxs.nl... Hi there,
I need to make a poisson distribution function that uses:
double Math.Exp(double d)
The d argument is a negative number in my case. When d becomes bigger and bigger, the result loses precision and is finally 0 (when d reaches
650) because it is too small to fit in a double. In my case, d can
become -10000, so I need to have a greater precision number and Exp function.
I've looked at decimal, but it cannot contain as small a number as double (just try to put a small double in a decimal and the decimal will be
0). Furthermore, there is no Math.Exp overload that takes decimals.
Any suggestions anyone? Thanks, Michel ms*@virtualsciences.nl
Michel & Eric, exp(-100) == exp(-10) * exp(-10)
in mathematical terms.
Nope, exp(-10) * exp(-10) == exp(-20)
Mattias
--
Mattias Sjögren [MVP] mattias @ mvps.org http://www.msjogren.net/dotnet/
Please reply only to the newsgroup.
Eric Gunnerson [MS] <er****@online.microsoft.com> wrote: exp(-100) == exp(-10) * exp(-10)
in mathematical terms.
No it doesn't. exp (-10) * exp(-10) = exp (-20)
Forget e here, let's take an example which is easier to work with: 3
3^2 * 3^3 = 9*27 = 243
3^(2*3) = 3^6 = 729
3^(2+3) = 3^5 = 243
In general, x^y * x^z = x^(y+z), not x^(y*z)
--
Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet
If replying to the group, please do not mail me too
Thanks Mattias and Jon - you are, of course, correct.
--
Eric Gunnerson
Visit the C# product team at http://www.csharp.net
Eric's blog is at http://blogs.gotdotnet.com/ericgu/
This posting is provided "AS IS" with no warranties, and confers no rights.
"Mattias Sjögren" <ma********************@mvps.org> wrote in message
news:uD**************@TK2MSFTNGP09.phx.gbl... Michel & Eric,
exp(-100) == exp(-10) * exp(-10)
in mathematical terms.
Nope, exp(-10) * exp(-10) == exp(-20) Mattias
-- Mattias Sjögren [MVP] mattias @ mvps.org http://www.msjogren.net/dotnet/ Please reply only to the newsgroup. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
by: f |
last post by:
I have this
double sum, a, b, c;
sum = a + b + c;
printf("%.20f = %.20f, %.20f, %.20f", sum, a, b, c);
I found that the debug version and release version of the same code
give me different...
|
by: Christian Christmann |
last post by:
Hi,
just a general question.
Which data type is more precise for large values:
float or double?
Thank you.
Chris
|
by: Bjørn Augestad |
last post by:
Below is a program which converts a double to an integer in two
different ways, giving me two different values for the int. The basic
expression is 1.0 / (1.0 * 365.0) which should be 365, but one...
|
by: Michel |
last post by:
Hi there,
I need to make a poisson distribution function that uses:
double Math.Exp(double d)
The d argument is a negative number in my case. When d becomes bigger and
bigger, the result...
|
by: Bryan Parkoff |
last post by:
The guideline says to use %f in printf() function using the keyword
float and double.
For example
float a = 1.2345;
double b = 5.166666667;
printf("%.2f\n %f\n", a, b);
|
by: lcw1964 |
last post by:
This may be in the category of bush-league rudimentary, but I am quite
perplexed on this and diligent Googling has not provided me with a
clear straight answer--perhaps I don't know how to ask the...
|
by: Dilip |
last post by:
Recently in our code, I ran into a situation where were stuffing a
float inside a double. The precision was extended automatically
because of that. To make a long story short, this caused...
|
by: Alexander Stoyakin |
last post by:
Hello,
please advise on the following issue. I need to check that difference
between two double values is not higher than defined limit.
int main()
{
double limit = 0.3;
double val1 = 0.5,...
|
by: md |
last post by:
Hi
Does any body know, how to round a double value with a specific number
of digits after the decimal points?
A function like this:
RoundMyDouble (double &value, short numberOfPrecisions)
...
|
by: CloudSolutions |
last post by:
Introduction:
For many beginners and individual users, requiring a credit card and email registration may pose a barrier when starting to use cloud servers. However, some cloud server providers now...
|
by: isladogs |
last post by:
The next Access Europe User Group meeting will be on Wednesday 3 Apr 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM).
In this session, we are pleased to welcome former...
|
by: taylorcarr |
last post by:
A Canon printer is a smart device known for being advanced, efficient, and reliable. It is designed for home, office, and hybrid workspace use and can also be used for a variety of purposes. However,...
|
by: Charles Arthur |
last post by:
How do i turn on java script on a villaon, callus and itel keypad mobile phone
|
by: ryjfgjl |
last post by:
In our work, we often receive Excel tables with data in the same format. If we want to analyze these data, it can be difficult to analyze them because the data is spread across multiple Excel files...
|
by: BarryA |
last post by:
What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...
|
by: nemocccc |
last post by:
hello, everyone, I want to develop a software for my android phone for daily needs, any suggestions?
|
by: Sonnysonu |
last post by:
This is the data of csv file
1 2 3
1 2 3
1 2 3
1 2 3
2 3
2 3
3
the lengths should be different i have to store the data by column-wise with in the specific length.
suppose the i have to...
|
by: Hystou |
last post by:
There are some requirements for setting up RAID:
1. The motherboard and BIOS support RAID configuration.
2. The motherboard has 2 or more available SATA protocol SSD/HDD slots (including MSATA, M.2...
| |