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Altera_Forum's avatar
Altera_Forum
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14 years ago

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?

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    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's avatar
    Altera_Forum
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    14 years ago

    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's avatar
    Altera_Forum
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    14 years ago

    thanks :)

    I have already read about the fixed point. But i'll do it one more time.
  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    --- 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.