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GNU Octave

4. Numeric Data Types

A numeric constant may be a scalar, a vector, or a matrix, and it may contain complex values.

The simplest form of a numeric constant, a scalar, is a single number that can be an integer, a decimal fraction, a number in scientific (exponential) notation, or a complex number. Note that all numeric constants are represented within Octave in double-precision floating point format (complex constants are stored as pairs of double-precision floating point values). Here are some examples of real-valued numeric constants, which all have the same value:

105 1.05e+2 1050e-1

To specify complex constants, you can write an expression of the form

3 + 4i 3.0 + 4.0i 0.3e1 + 40e-1i

all of which are equivalent. The letter `i' in the previous example stands for the pure imaginary constant, defined as sqrt (-1).

For Octave to recognize a value as the imaginary part of a complex constant, a space must not appear between the number and the `i'. If it does, Octave will print an error message, like this:

octave:13> 3 + 4 i parse error: 3 + 4 i ^

You may also use `j', `I', or `J' in place of the `i' above. All four forms are equivalent.

4.1 Matrices
4.2 Ranges
4.3 Predicates for Numeric Objects