I’ve started a new blog, which I’ll be sharing with a couple of colleagues. In brief, the idea is to try to do a “hobby” project as well as possible, the whole purpose being the learning experience.
Rather than waffle on about it here, I’ll just refer you to the blog of the
Quest for the Perfect Project. Hope it’s of some interest to some of you.
Oh, and this blog will carry on as normal.
Jon Skeet's coding blog 
Hello!
Ive seen some of your articles about decimal and floating point type numbers, I hope you can help me:
I’m building a program in which I have to add 9 numbers. I’m using double type numbers. When I don’t round the numbers, the results I get are a bit “crazy”. The results are all having one digit too much and all of them are not accure.
The numbers we sum:
0.859106534595483 +
0.859106524783344 +
0.859106524764621 +
0.853713209485585 +
0.853713197409835 +
0.853713197386032 +
0.853746263543208 +
0.853746250367769 +
0.853746250340519 =
The C#.net compiler gives us
7.6996979526763969
0.853746250340519 +
0.853713197386032 +
0.859106524764621 +
0.853746250367769 +
0.853713197409835 +
0.859106524783344 +
0.853746263543208 +
0.853713209485585 +
0.859106534595483 =
The C#.net compiler gives us
7.6996979526763951
A simple calculator gives us to both of them (since we add the same numbers in diferent order)
7.6996979526763960
When I devided the equation to simpler equations I have found the first “mistake” here:
1.707459447726551+
0.859106524764621=
The C#.net compiler gives us
2.5665659724911718
A simple calculator gives us
2.566565972491172
Yours,
Vitali
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Please mail me about the floating point problem – it’s not really the kind of thing to discuss on a blog, nor is the post even vaguely related to floating point.
Jon
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