FP epsilon estimation in Fortran

Floating-point epsilon estimation in retro Fortran no-talking, in emulated 80286 / MS-DOS machine in DOSbox. This program implements floating-point 'epsilon' estimation in retro Fortran no-talking, in emulated 80286 / MS-DOS machine in DOSbox. This very short code demonstrates how easy it is to get the actual FP accuracy, i.e., the significant decimal digits in FP arithmetic operations. The result in Fortran 77 is seven FP digits for REAL type and 15 digits for DOUBLE PRECISION type, which are consistent with 2-byte and 4-byte float types, correspondingly, used in other programming languages of that era like C.

Warning: In some older versions of Microsoft's Fortran 77, the batch process 'FORT.BAT' assumed that the input filename is given as argument *without* the '.FOR' extension. If it is given, then the output is unpredictable and usually results in a corrupted *original* (source) file! Make sure to always keep backup before compiling - I had to write the source code twice because of this.

Enable captions for more details and walk-through. Source code available at the Github repository (see channel info).

Tags: #asmr #coding #programming #notalking #fortran #retro #msdos #dosbox

Comments

Post a Comment

Popular Posts

Hello x86: Low-level assembly coding for the 8086

Image
Hello x86: Low-level assembly coding for the 8086 wiring no-talking, in emulated 80286 / MS-DOS machine in DOSbox. This is a set of four "hello world" codes in x86 assembly, using single-segment 16-bit/i8086 instruction set. The purspose of this tutorial is to demonstrate how exact, minimal-space, yet razor-sharp is assembly coding, especially when dealing with such complexities like the segmented memory model of MS-DOS. The four versions are: Hello1.asm: Old-style standard directives, used by '70s-'80s assemblers, for .EXE output. Hello1C.asm: Old-style standard directives, used by '70s-'80s assemblers, for .COM output. Hello2.asm: Compact 'dot' directives, used by modern assemblers, for .EXE output. Hello2C.asm: Compact 'dot' directives, used by modern assemblers, for .COM output. The difference between .EXE and .COM comes from the MS-DOS era, when the first format required 'far' pointers (segment:offset) for memory ad
Read more

Announcement: Writing a new book in Data Science and R&D projects

Image
About two years ago an idea was hovering through my mind, a question actually: Why is that “traditional” project managers fail so gloriously in managing teams, especially in the Research and Development (R&D) field of work? I let it mature for a while, thinking that someone will eventually write a book or something about it. Two years have passed and no one did it, so I figured, well, I guess I will have to do that myself. After sending the proposal to only few top publishers, I was privileged enough to land a book contract with Elsevier , which was indeed my first choice for this endeavor.  The subject of the book will be simple: Managing and coordinating teams in the R&D environment, specifically in the domains of Data Analytics, Machine Learning and Artificial Intelligence in general , where I have been working for more than two and a half decades as a professional. Specifically, it will focus on every aspect of teamwork from the first to the last day of a R&D project, i
Read more

Fibonacci numbers in C (4 different ways)

Image
Fibonacci series in pure C no talking, using only vim and gcc in terminal, implementing four alternative designs: 1) Recursive: using the typical mathematical definition for Fib(n) 2) Iterative: using loop instead of recursion to avoid call stack overflows 3) Dynamic Programming: using buffer for cached results, calculated only once 4) Analytical: using the solution of the differential equation for Fib(n) Each option has its pros and cons, typically trading code simplicity for resources (recursion) or trading memory (cache) for speed. The purpose of this tutorial is to demonstrate coding discipline when working with very limited coding tools (command-line only in terminal) and alternative designs for use in different situations. Inline comments describe details about the code being written. Enable captions for more information on what is happening in each section of the video. Enable captions for more details and walk-through. Source code available at the Github repository (see chann
Read more

Multiplication tables in COBOL

Image
This program is a simple demonstration of basic user I/O and arithmetic operations in one of the earliest versions of COBOL that was made available for home computers in the early '80s. The "executable" was actually an intermediate binary format created as the compiler output, which could then be executed by another program, not very differently than today's Just-In-Time (JIT) compilers or pre-compiled interpreted languages. The language is the creation of Grace Hopper, a pivotal figure in the evolution of programming and the design of the first trully general-purpose languages. The two main strengths of COBOL was the rich I/O functionality for data file handling and the screen handling routines for creating terminal-based user I/O via forms and tables. Although functionally limited and with loquacious syntax by the programming standards of later language generations, COBOL was deemed extremely reliable and understandable by the programmers of those early days. So m
Read more

Bricks and towers in Prolog

Image
This program is a simple demonstration for illustrating how classic declarative programming can provide very intuitive and compact solution generators for logic problems and combinatorial tasks. In this example, a set of bricks with three sizes and a stability constraint ("do not put larger above") is coded to provide solution searching on all possible ways to build a stable tower of a specific height. Prolog's main advantage over other declarative programming languages is that even in the early '80s came with a rich library of common functionalities that made real-world application development easy. Turbo Prolog was probably the best option for PC machines, with efficient memory enhancements via more strict typing and other syntax shortcuts to limit the tree search in manageable space/time requirements for these platforms. Although now depricated by constrained and fuzzy logic paradigms, Prolog-style programming is still the most intuitive way to design simple expe
Read more

Channel Updates

Loading...