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ALTFP_INV_SQRT problem

Altera_Forum
Honored Contributor II
‎08-25-2011 01:00 PM
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I have instanced ALTFP_INV_SQRT (y = 1/sqrt(y)) mega function in Quartus 10. I’m using single precision. When I calculate X”3F800001" (almost 1) the result is X”3F000000” (0.5). Calculating X” 3F800000" and X” 3F800002" is OK as shown below. 

 

Simulations: 

 

X"3F800000" => X"3F800000" or 

1,0000000000000000 => 1,0000000000000000 

X"3F800001" => X"3F000000" or 

1,0000001192092896 => 0,5000000000000000 -ERROR 

X"3F800002" => X"3F7FFFFE" or 

1,0000002384185791 => 0,9999998807907104
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Altera_Forum
Honored Contributor II
‎08-25-2011 01:54 PM
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Looks like a bug. File a support request.

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Altera_Forum
Honored Contributor II
‎08-25-2011 02:43 PM
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OK 

 

Thanks
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