Why is MATLAB rounding this?

4 次查看（过去 30 天）
Sam Falzone
Sam Falzone 2011-2-13
I have a part of my code:
eps = 10^(log10(eps) + 0.125);
The program will round it off. For instance, if the original value of eps is 2, the calculated value is 133. This is rounded. If I do the same code in the command window, it gives me the correct value, which is a decimal.
If I run the code:
eps = 10^(log10(eps) - 0.125);
and the original value of eps is 0, it returns 0, and the while loop I have it in blows up.
I would like to stop it from rounding. These take place in a nested if statement, within a while loop.
  4 个评论
显示 2更早的评论
Bruno Luong
Bruno Luong 2011-2-13
Please write what do you expect and you get with a concrete value for eps (and btw change the name eps to something else as Oleg suggested).
Paulo Silva
Paulo Silva 2011-2-13
So you want matlab to give 10^-Inf instead of zero?

请先登录，再进行评论。

请先登录，再回答此问题。

回答（3 个）

Bruno Luong
Bruno Luong 2011-2-13
a = 2
fprintf('%1.16e', 10^(log10(a) + 0.125))
2.6670428643266479e+000
What's your problem???
  4 个评论
显示 2更早的评论
Oleg Komarov
Oleg Komarov 2011-2-14
It doesn't give me any problem. What you do before that in your code? Do you have a variable log10 defined, or a self-written log10 fcn?
Paulo Silva
Paulo Silva 2011-2-14
I wonder why is Sam messing around with matlab built in functions?!

请先登录，再进行评论。

Jan
Jan 2011-2-14
If you use INT2STR to display the result, the printed number is rounded - read the help text of INT2STR! Use NUM2STR or SPRINTF instead to get the decimals.
Try Bruno's example and post, if it runs as wanted.
Walter Roberson
Walter Roberson 2011-2-14
Double-check to see which "format" you have in effect. And if you are using a variable for the "100" part, check the data class of the variable: if it happened to be one of the integer types then the answer would be integer.

类别

在 Help Center 和 File Exchange 中查找有关 Logical 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by