Stream: helpdesk (published)

Topic: How to extract exponent from scientific notation?

Júlio Hoffimann (Mar 22 2025 at 12:58):

Given a number, say x = 1e-5, how would you extract the number 5?

One possible solution is round(Int, -log10(x)). Is there any special function in Base with this purpose?

Mosè Giordano (Mar 22 2025 at 14:58):

Base.hidigit, but that's internal and does similar things anyway

Mosè Giordano (Mar 22 2025 at 14:59):

But are you sure about round? Is what you want? 5e-5 would be different from 1e-5, is that what you want?

Júlio Hoffimann (Mar 22 2025 at 15:11):

Not sure about the round, just wanted to get an integer as the result

Mosè Giordano (Mar 22 2025 at 15:24):

Let's change the question: _what_ integer do you want based on the given input? Your request is under specified, there's lots of ambiguity

Júlio Hoffimann (Mar 22 2025 at 15:52):

Assuming that the value x is a tolerance to floating point approximations, I'm trying to extract the number of digits that make a difference. So if two numbers are subtracted I'm expecting to represent the difference with this number of digits

Last updated: Apr 04 2025 at 04:42 UTC