ChangePrecision

This package makes it easy to change the "default" precision of a large body of Julia code, simply by prefixing it with the @changeprecision T expression macro, for example:

@changeprecision Float32 begin
    x = 7.3
    y = 1/3
    z = rand() .+ ones(3,4)
end

In particular, floating-point literals like 7.3 are reinterpreted as the requested type Float32, operations like / that convert integer arguments to Float64 instead convert to Float32, and random-number or matrix constructors like rand and ones default to Float32 instead of Float64. Several other cases are handled as well: arithmetic with irrational constants like pi, linear-algebra functions (like inv) on integer matrices, etcetera.

The @changeprecision transformations are applied recursively to any include(filename) call, so that you can simply do @changeprecision Float32 include("mycode.jl") to run a whole script mycode.jl in Float32 default precision.

Code that explicitly specifies a type, e.g. rand(Float64), is unaffected by @changeprecision.

Note that only expressions that explicitly appear in the expression (or code inserted by include) are converted by @changeprecision. Code hidden inside external functions that are called is not affected.

This package was designed for quick hacks, where you want to experiment with the effect of a change in precision on a bunch of code. For production code and long-term software development in Julia, you are strongly urged to write precision-independent code — that is, your functions should determine their working precision from the precision of their arguments, so that by simply passing data in a different precision they compute in that precision.