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Altera_Forum
Honored Contributor
Honored Contributorsqrtf custom instruction gives sometimes absolutely wrong results
I use Quartus 13.1.0.182 web edition with a Cyclone III FPGA The project is compiled with the Floating point custom instruction 2.0 from Qsys. My code calculates the square root and some time...
Altera_ForumHonored Contributor
Honored ContributorLooks that way, probably failing to increment the exponent when the mantissa is rounded up.
FWIW you'll probably get better precision from calculating one of sqrt((1+sin)*(1-sin)) or sqrt(0.5 - sin*sin + 0.5).
