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<< >> shift in Matlab?

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Bob Li
Bob Li 2011-10-14
In C, bitwise shift can be done using '<<, >>, which are even combined with assignment operators into '<<=, >>=.
In Matlab, I found functions like bitshift, bitsll, bitsra, bitsrl
Which are far less convenient than '<< >> operators. Is there any better way to do shifting.

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Jan
Jan 2011-10-14
No. There is no better way in Matlab. There are no >>= or similar inplace operators. This is a principal limitation of Matlab's internal data management.
You can shift by multiplying powers of 2. This has been faster than BITSHIFT in old Matlab releases. But today BITSHIFT is more efficient.
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Walter Roberson
Walter Roberson 2011-10-14
If you use the multiplication approach, be careful about value saturation. When you use an int or uint data type, MATLAB does not simply discard bits that would "fall off the end": instead when it detects that the value would be above the numeric maximum for the data type, it sets the result to the numeric maximum for the datatype.
uint8(129) * uint8(2) does not, for example, become 128*2 + 1*2 with the 128*2 discarded: the result would be uint8(255), the maximum uint8 value.
Bob Li
Bob Li 2011-10-15
Walter,
This behavior is somewhat different from C. C truncates over/underflow, while MATLAB clamps. I just read them on the Programming Fundamentals.
Thanks for reminding.

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