[gdal-dev] Using bitwise & with muparser VRT expressions

[Even Rouault]

Le 04/12/2025 à 16:45, Hugh Graham a écrit :
> Many thanks to all - this is very helpful.
>
> Dan, I'll explore some of these other options you mention. In this new 
> PR, is it the case that by switching to using theLLVM dialect these 
> operators will automatically be recognised? I suppose if this is the 
> case then explicitly adding the operator might not strictly be 
> necessary...
Yes,  with the LLVM dialect, if your input bands are of integer type and 
you specify an output integer type, bitwise and will be done in the 
integer domain.
>
> Also, I appreciate the clarification that values are always 
> converted to float during the arithmetic, I agree, Javier, that in 
> this case a bitwise operation is a bit strange...

When using muparser, yes they are converted to double, since its 
"official" API only exposes that data type. But if the absolute value of 
integer values is below 1 << 53, they are perfectly represented as a 
double, so this is generally not much of an issue.


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