CLHS: Function COMPLEX

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Function COMPLEX

Syntax:

complex realpart `&optional` imagpart => complex

Arguments and Values:

realpart---a real.

imagpart---a real.

complex---a rational or a complex.

Description:

complex returns a number whose real part is realpart and whose imaginary part is imagpart.

If realpart is a rational and imagpart is the rational number zero, the result of complex is realpart, a rational. Otherwise, the result is a complex.

If either realpart or imagpart is a float, the non-float is converted to a float before the complex is created. If imagpart is not supplied, the imaginary part is a zero of the same type as realpart; i.e., `(coerce 0 (type-of` realpart`))` is effectively used.

Type upgrading implies a movement upwards in the type hierarchy lattice. In the case of complexes, the type-specifier must be a subtype of `(upgraded-complex-part-type` type-specifier`)`. If type-specifier1 is a subtype of type-specifier2, then `(upgraded-complex-element-type '`type-specifier1`)` must also be a subtype of `(upgraded-complex-element-type '`type-specifier2`)`. Two disjoint types can be upgraded into the same thing.

Examples:

     (complex 0) =>  0
     (complex 0.0) =>  #C(0.0 0.0)
     (complex 1 1/2) =>  #C(1 1/2)
     (complex 1 .99) =>  #C(1.0 0.99)
     (complex 3/2 0.0) =>  #C(1.5 0.0)

Side Effects: None.

Affected By: None.

Exceptional Situations: None.

See Also:

realpart, imagpart, Section 2.4.8.11 (Sharpsign C)

Notes: None.

The following X3J13 cleanup issue, not part of the specification, applies to this section:

- ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING

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