Complex.ToString format changed to <a; b>
To better support formatting values with culture-specific information, the default string representation of complex numbers was changed to avoid using characters that can be used in formatted numeric values. This change affects Complex.ToString, where the value is now formatted as <a; b> instead of (a, b). Both a and b are formatted using the general format specifier ("G") and the conventions of the culture defined by provider—this hasn't changed.
Previous behavior
Previously, the string representation of the complex number returned by Complex.ToString displayed the number using its Cartesian coordinates in the form (a, b), where a was the real part of the complex number, and b was its imaginary part.
New behavior
Starting in .NET 8, the string representation of the complex number returned by Complex.ToString displays the number using its Cartesian coordinates in the form <a; b>, where a is the real part of the complex number, and b is its imaginary part.
Version introduced
.NET 8
Type of breaking change
This change is a behavioral change.
Reason for change
The change to use a semicolon enables support of formatting with culture-specific information. It also enables the corresponding need to be able to parse results back out given that it implements INumberBase<TSelf>.
The change from parentheses (( )) to angle brackets avoids potential collision with numeric formats where negative numbers are formatted as (x). The new behavior is also consistent with the behavior of the Vector* types.
Recommended action
If you need the previous format, you can use a custom string formatting mechanism such as $"({complex.Real}, {complex.Imaginary})" to produce a string in that format.
