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# 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 by default numeric constants are represented within Octave in double-precision floating point format (complex constants are stored as pairs of double-precision floating point values). It is however possible to represent real integers as described in Integer Data Types. 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: syntax error >>> 3 + 4 i ^ |

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

__Built-in Function:__**double***(*`x`)Convert

`x`to double precision type.**See also:**single.

__Built-in Function:__**complex***(*`x`)__Built-in Function:__**complex***(*`re`,`im`)Return a complex result from real arguments. With 1 real argument

`x`, return the complex result

. With 2 real arguments, return the complex result`x`+ 0i

.`re`+`im``complex`

can often be more convenient than expressions such as`a + i*b`

. For example:complex ([1, 2], [3, 4]) ⇒ 1 + 3i 2 + 4i

4.1 Matrices | ||

4.2 Ranges | ||

4.3 Single Precision Data Types | ||

4.4 Integer Data Types | ||

4.5 Bit Manipulations | ||

4.6 Logical Values | ||

4.7 Promotion and Demotion of Data Types | ||

4.8 Predicates for Numeric Objects |

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