# Logarithm

Discussion in 'Homework Help' started by serial2222, Dec 27, 2014.

1. ### serial2222 Thread Starter New Member

Dec 27, 2014
9
0
hi friends
i have problem with logic works
i need Logarithm circuit with "logic works"
can someone help me????
plzzzzzzzz

2. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
First, what kind of logarithm circuit are you talking about? Analog, digital, ...?

This is not the Homework Done For You forum. You need to show YOUR best attempt to solve YOUR homework problem. We will then help guide you along the path to the solution if we can.

3. ### serial2222 Thread Starter New Member

Dec 27, 2014
9
0
i exactly dont know what kind ? analog or digital?
but i not one kind electric circuit diagram can be design with logic work
like this : http://t0.gstatic.com/images?q=tbn:ANd9GcSHOVeCKma5-JakuSBwuYzJ0m3N7vFPyE-Qq4Lm494X1M5c0IMo
but i say i become dizzy (
help me plzzzzzzz

4. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
So what, exactly, is the assignment?

5. ### serial2222 Thread Starter New Member

Dec 27, 2014
9
0
Log 2 (A) + Log 2 (B )

6. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
How are A and B represented?

serial2222 likes this.
7. ### serial2222 Thread Starter New Member

Dec 27, 2014
9
0
in digital mode

8. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
Again, how are the values A and B represented? Unsigned integers? Two-complement? IEEE Floating point?

What, exactly, is the assignment?

serial2222 likes this.
9. ### serial2222 Thread Starter New Member

Dec 27, 2014
9
0
two - comlement ==> true table ===> karno ===> equation ===> circuit

10. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
Okay. So focus on taking the base-2 logarithm of a two's complement number.

What representation is the output supposed to be in?

11. ### serial2222 Thread Starter New Member

Dec 27, 2014
9
0
yes.
in seven segment

12. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
"seven segment" is not a representation format. A representation format is something like "unsigned binary", "twos-complement", "IEEE-754 single-precision floating point", "fixed point".

13. ### serial2222 Thread Starter New Member

Dec 27, 2014
9
0
oh ye
twos-complement and show result in seven segment

14. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
Okay.

So what should the output of your circuit be if the input is 5? What should be displayed?

What if the input is -12?

Dec 27, 2014
9
0
shows error

16. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
For both cases?

How does it show an error?

What values of input should it NOT show an error for?

17. ### serial2222 Thread Starter New Member

Dec 27, 2014
9
0

more intricacy accord

18. ### WBahn Moderator

Mar 31, 2012
18,079
4,917
I don't understand what you are saying here. I suspect it is just a language barrier problem, so try rephrasing.

You said that if you have an input value of 5 that the output should show error. So in response to that I have two questions:

Why should the base-2 logarithm of 5 produce an error?

How will you show an error on your 7-segment displays?

In addition, I asked you to describe what input values (at least give an example or two) should not produce an error and what the output values should then be.