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Remove integer domain example that doesn't work #31298

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merged 4 commits into from
Mar 14, 2019
Merged

Remove integer domain example that doesn't work #31298

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1ae5ff9
Update integer literal example to reflect smarter interpretation of e…
AnjoMan Mar 10, 2019
43a5d9e
Drop mention of integer size
AnjoMan Mar 10, 2019
2f323ee
Add an extra example of how to fix an exponent domain error
AnjoMan Mar 10, 2019
5ccdc99
Fix a sign error in documentation
AnjoMan Mar 14, 2019
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5 changes: 3 additions & 2 deletions base/intfuncs.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -175,8 +175,9 @@ to_power_type(x) = convert(Base._return_type(*, Tuple{typeof(x), typeof(x)}), x)
"\nConvert input to float.")))
@noinline throw_domerr_powbysq(::Integer, p) = throw(DomainError(p,
string("Cannot raise an integer x to a negative power ", p, '.',
"\nMake x a float by adding a zero decimal (e.g., 2.0^$p instead ",
"of 2^$p), or write 1/x^$(-p), float(x)^$p, or (x//1)^$p")))
"\nMake x or $p a float by adding a zero decimal ",
"(e.g., 2.0^$p or 2^$(float(p)) instead of 2^$p), ",
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@Keno I think this addresses your point about the error message suggestion. It adds a suggestion for 2^-1.0, as well as calling float on the exponent (i.e. 2^(float(p))) which should cover the literal and expression cases.

"or write 1/x^$(-p), float(x)^$p, x^float($p) or (x//1)^$p")))
@noinline throw_domerr_powbysq(::AbstractMatrix, p) = throw(DomainError(p,
string("Cannot raise an integer matrix x to a negative power ", p, '.',
"\nMake x a float matrix by adding a zero decimal ",
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6 changes: 3 additions & 3 deletions doc/src/manual/noteworthy-differences.md
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Expand Up @@ -18,9 +18,9 @@ may trip up Julia users accustomed to MATLAB:
which grow `Vector`s much more efficiently than MATLAB's `a(end+1) = val`.
* The imaginary unit `sqrt(-1)` is represented in Julia as [`im`](@ref), not `i` or `j` as in MATLAB.
* In Julia, literal numbers without a decimal point (such as `42`) create integers instead of floating
point numbers. Arbitrarily large integer literals are supported. As a result, some operations
such as `2^-1` will throw a domain error as the result is not an integer (see [the FAQ entry on domain errors](@ref faq-domain-errors)
for details).
point numbers. As a result, some operations can throw
a domain error if they expect a float; for example, `julia> a = 1; 2^a` throws a domain error, as the
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result is not an integer (see [the FAQ entry on domain errors](@ref faq-domain-errors) for details).
* In Julia, multiple values are returned and assigned as tuples, e.g. `(a, b) = (1, 2)` or `a, b = 1, 2`.
MATLAB's `nargout`, which is often used in MATLAB to do optional work based on the number of returned
values, does not exist in Julia. Instead, users can use optional and keyword arguments to achieve
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