Why is half-precision slower than double-precision?

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While executing same calculations in MATLAB, speed of double-precision variables is faster than half-precision.
Is this normal? Is there any way to speed up?

Accepted Answer

MathWorks Support Team
MathWorks Support Team on 19 Aug 2019
This is true.
n = 100;
t1= zeros(1,n);
t2= zeros(1,n);
for i = 1:n
a = ones(10,10,100,100);
b = zeros(10,10,100,100);
a2 = half(a);
b2 = half(b);
tic
temp = plus(a,b);
c = sum(temp(:));
t1(i) = toc;
tic
temp2 = plus(a2,b2);
c2 = sum(temp2(:));
t2(i) = toc;
end
sum(t1)
sum(t2)
ans =
0.1456
ans=
0.2737
Computations with half-precision data types is slower than those with double precision data types. This is because, unlike double, half-precision is not a native data type in MATLAB and hence, requires additional tweak to do the computations.

More Answers (1)

Krishna Bindumadhavan
Krishna Bindumadhavan on 9 Apr 2020
Edited: MathWorks Support Team on 22 Sep 2021
To accelerate half precision floating point math, from 20a onwards, you can now generate CUDA code from your MATLAB Algorithm for NVIDIA GPU's with Compute Capability > 5.3 which have native half precision floating point support: https://www.mathworks.com/help/gpucoder/ug/sobel-edge-detection-in-half-precision.html.

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