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GNU Octave Manual Version 3
by John W. Eaton, David Bateman, Søren Hauberg
Paperback (6"x9"), 568 pages
ISBN 095461206X
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4.3.1 Integer Arithmetic

Octave supports some integer operations such as addition and multiplication. The operators +, -, .*, and ./ work on integers of the same type. So, it is possible to add two 32 bit integers, but not to add a 32 bit integer and a 16 bit integer.

The arithmetic operations on integers are performed by casting the integer values to double precision values, performing the operation, and then re-casting the values back to the original integer type. As the double precision type of Octave is only capable of representing integers with up to 53 bits of precision, it is not possible to perform arithmetic with 64 bit integer types.

When doing integer arithmetic one should consider the possibility of underflow and overflow. This happens when the result of the computation can't be represented using the chosen integer type. As an example it is not possible to represent the result of 10 - 20 when using unsigned integers. Octave makes sure that the result of integer computations is the integer that is closest to the true result. So, the result of 10 - 20 when using unsigned integers is zero.

When doing integer division Octave will round the result to the nearest integer. This is different from most programming languages, where the result is often floored to the nearest integer. So, the result of int32(5)./int32(8) is 1.

ISBN 095461206XGNU Octave Manual Version 3See the print edition