Fortran 2018 conformance with ISO/IEC/IEEE 60559:2011

Author(s):  
Michael Metcalf ◽  
John Reid ◽  
Malcolm Cohen

A large number of changes to the intrinsic modules ieee_arithmetic, ieee_exceptions, and ieee_features have been made for conformance with the new IEEE standard for floating-point arithmetic (ISO/IEC/IEEE 60559:2011), including hexadecimal-significand I/O.

2021 ◽  
Vol 37 (2) ◽  
pp. 355-360
Author(s):  
RADU T. TRÎMBIŢAŞ

We study the strange behavior in floating-point arithmetic of a function proposed by Nicholas Higham, consisting of repeated square roots extraction followed by the same number of times squaring and find its fixpoints. For IEEE standard double precision floating point numbers the fixpoints have the form \[ x \in \left\{\left( 1+k\mathrm{eps}\right) ^{\frac{1}{\mathrm{eps}}},\quad k=\left[ -745:\frac{1}{2}:-\frac{1}{2},0:709\right]\right\} \cup \{0\} , \] where \mathrm{eps} is the machine epsilon."


Author(s):  
Michael Metcalf ◽  
John Reid ◽  
Malcolm Cohen

Exception handling is required for the development of robust and efficient numerical software, a principal application of Fortran. Indeed, the existence of such a facility makes it possible to develop more efficient software than would otherwise be possible. Most computers nowadays have hardware based on the IEEE standard for binary floating-point arithmetic, which later became an ISO standard. Therefore, the Fortran exception handling features are based on the ability to test and set the five flags for floating-point exceptions that the IEEE standard specifies.


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