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decimal fraction

Altera_Forum
Honored Contributor II
1,829 Views

Hi, 

How can I convert the decimal fraction to the mantissa format (IEEE). The MegaWizard function demands the decimal number in binary form (3 = 0011, for example). So how can I convert 0.3 to mantissa without multipling on 10 or 100 etc? Other way, if i starting to multiply so i don't net to use mantissa, am i wright? 

 

My final target is to apply the next math function y = 0.201x + 7.899 

I supplying the "x" values. 

 

Can anybody help me with this question, please?
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5 Replies
Altera_Forum
Honored Contributor II
82 Views

the input is an integer, which will always be binary. But in fixed point, the integer and fractional parts are just normal integers offset by 2^n. Have a read up on fixed point number formats. 

 

Are you sure you want to use flooating point?
Altera_Forum
Honored Contributor II
82 Views

I am not sure :) 

Are u talkin about the fixed point of MegaWizard? As i remember, it's posibble when i am choosing to use ALTFP_CONVERT. 

 

Altera_Forum
Honored Contributor II
82 Views

I suggest you read up on fixed point arithmatic 

http://en.wikipedia.org/wiki/fixed-point_arithmetic 

 

All integers are in 2s compliment - there is no decimal representation in any electronics.
Altera_Forum
Honored Contributor II
82 Views

thanks :) 

I have already read about the fixed point. But i'll do it one more time.
Altera_Forum
Honored Contributor II
82 Views

 

--- Quote Start ---  

All integers are in 2s compliment - there is no decimal representation in any electronics. 

--- Quote End ---  

 

 

Not entirely true! 

Some old processors (eg the Singer 'System 10' and its descendent the ICL 'System 25') used BCD arithmetic and addressing.
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