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Altera_Forum

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05-14-2012
11:56 AM

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decimal fraction

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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Altera_Forum

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05-14-2012
12:46 PM

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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?
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Altera_Forum

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05-15-2012
04:07 AM

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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.
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Altera_Forum

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05-15-2012
06:46 AM

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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.
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Altera_Forum

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05-15-2012
07:01 AM

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thanks :)

I have already read about the fixed point. But i'll do it one more time.
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--- 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.

Altera_Forum

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05-15-2012
08:36 AM

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For more complete information about compiler optimizations, see our Optimization Notice.