I am trying to increment a code that uses the setprecision function, but every time I use an example, however simple, it always gives the same error.
when I do:
x = big"1.23456789" setprecision(x, 20)
I get the following error:
ERROR: LoadError: MethodError: no method matching setprecision(::BigFloat, ::Int64)
Closest candidates are:
setprecision(::Type{BigFloat}, ::Integer; base) at mpfr.jl:840
setprecision(::Function, ::Integer; base) at mpfr.jl:969
Stacktrace:
[1] top-level scope
The setprecision function accepts a type, and globally sets the precision for all operations on this type (there is a variant that does this temporary, but let me focus on a simpler scenario). So what you should do is for example:
julia> setprecision(BigFloat, 20) # low precision
20
julia> x = big"1.23456789"
1.2345676
julia> setprecision(BigFloat, 200) # higher precision
200
julia> x = big"1.23456789"
1.2345678900000000000000000000000000000000000000000000000000004
After setprecision all operations on BigFloat values will use the precision you set.
Note that you should set precision first and only next perform some operation. See an example:
julia> x = big"1.23456789"
1.234567889999999999999999999999999999999999999999999999999999999999999999999998
julia> setprecision(BigFloat, 20)
20
julia> x # still high precision because we created x before changing precision
1.234567889999999999999999999999999999999999999999999999999999999999999999999998
julia> x * 1 # the result of computation has lower precision since it is computed after calling setprecision
1.2345676