casting without rounding using coder

How can I manually trigger casting from a float/double to integer without involving any rounding while using coder?
LUT = single(rand(1,2000)*200);
for i=1:2000
ind = int32(LUT(i));
fprintf("%i\n",ind);
end
When the C++ code is generated it will be similar to:
int ind = static_cast<int>(rt_roundf_snf(LUT[i]));
I am aware that under certain circumstances coder is able to automatically figure out the optimal datatypes for indexing inside for loops resulting then in the desired result:
int ind = static_cast<int>(LUT[i]);

Respuestas (1)

Bjorn Gustavsson
Bjorn Gustavsson el 12 de Jul. de 2022
Well, the only interpretation I can thing of that matches the "casting without rounding" in a sensible way is:
ind = int32(floor(LUT2(i));
That way ind will be the integer part of whatever LUT2 is. But this is still "rounding-off the fractional part".
HTH

4 comentarios

Marc Barnada
Marc Barnada el 15 de Jul. de 2022
Unfortunately my interest is to simply trigger a plain static_cast<int> call without flooring, ceiling or rounding.
Bjorn Gustavsson
Bjorn Gustavsson el 15 de Jul. de 2022
What is the crucial difference?
Marc Barnada
Marc Barnada el 18 de Jul. de 2022
I want to have highly efficient C++ code, and that extra call to rt_roundf_snf has a big impact in the timings of a Look-Up-Table (LUT) function.
Bjorn Gustavsson
Bjorn Gustavsson el 18 de Jul. de 2022
If it is a limited point-of-use and a one-time effort would it be possible to manually edit the generated code?

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Versión

R2021a

Preguntada:

el 12 de Jul. de 2022

Comentada:

el 18 de Jul. de 2022

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