Writing Fast Fortran Routines for Python
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Introduction to Programming in Fortran 77 for Students of Science and Engineering
Introduction to programming in Fortran 77 for students of Science and Engineering Roman GrÄoger University of Pennsylvania, Department of Materials Science and Engineering 3231 Walnut Street, O±ce #215, Philadelphia, PA 19104 Revision 1.2 (September 27, 2004) 1 Introduction Fortran (FORmula TRANslation) is a programming language designed speci¯cally for scientists and engineers. For the past 30 years Fortran has been used for such projects as the design of bridges and aeroplane structures, it is used for factory automation control, for storm drainage design, analysis of scienti¯c data and so on. Throughout the life of this language, groups of users have written libraries of useful standard Fortran programs. These programs can be borrowed and used by other people who wish to take advantage of the expertise and experience of the authors, in a similar way in which a book is borrowed from a library. Fortran belongs to a class of higher-level programming languages in which the programs are not written directly in the machine code but instead in an arti¯cal, human-readable language. This source code consists of algorithms built using a set of standard constructions, each consisting of a series of commands which de¯ne the elementary operations with your data. In other words, any algorithm is a cookbook which speci¯es input ingredients, operations with them and with other data and ¯nally returns one or more results, depending on the function of this algorithm. Any source code has to be compiled in order to obtain an executable code which can be run on your computer. -
Fortran Resources 1
Fortran Resources 1 Ian D Chivers Jane Sleightholme May 7, 2021 1The original basis for this document was Mike Metcalf’s Fortran Information File. The next input came from people on comp-fortran-90. Details of how to subscribe or browse this list can be found in this document. If you have any corrections, additions, suggestions etc to make please contact us and we will endeavor to include your comments in later versions. Thanks to all the people who have contributed. Revision history The most recent version can be found at https://www.fortranplus.co.uk/fortran-information/ and the files section of the comp-fortran-90 list. https://www.jiscmail.ac.uk/cgi-bin/webadmin?A0=comp-fortran-90 • May 2021. Major update to the Intel entry. Also changes to the editors and IDE section, the graphics section, and the parallel programming section. • October 2020. Added an entry for Nvidia to the compiler section. Nvidia has integrated the PGI compiler suite into their NVIDIA HPC SDK product. Nvidia are also contributing to the LLVM Flang project. Updated the ’Additional Compiler Information’ entry in the compiler section. The Polyhedron benchmarks discuss automatic parallelisation. The fortranplus entry covers the diagnostic capability of the Cray, gfortran, Intel, Nag, Oracle and Nvidia compilers. Updated one entry and removed three others from the software tools section. Added ’Fortran Discourse’ to the e-lists section. We have also made changes to the Latex style sheet. • September 2020. Added a computer arithmetic and IEEE formats section. • June 2020. Updated the compiler entry with details of standard conformance. -
Scope in Fortran 90
Scope in Fortran 90 The scope of objects (variables, named constants, subprograms) within a program is the portion of the program in which the object is visible (can be use and, if it is a variable, modified). It is important to understand the scope of objects not only so that we know where to define an object we wish to use, but also what portion of a program unit is effected when, for example, a variable is changed, and, what errors might occur when using identifiers declared in other program sections. Objects declared in a program unit (a main program section, module, or external subprogram) are visible throughout that program unit, including any internal subprograms it hosts. Such objects are said to be global. Objects are not visible between program units. This is illustrated in Figure 1. Figure 1: The figure shows three program units. Main program unit Main is a host to the internal function F1. The module program unit Mod is a host to internal function F2. The external subroutine Sub hosts internal function F3. Objects declared inside a program unit are global; they are visible anywhere in the program unit including in any internal subprograms that it hosts. Objects in one program unit are not visible in another program unit, for example variable X and function F3 are not visible to the module program unit Mod. Objects in the module Mod can be imported to the main program section via the USE statement, see later in this section. Data declared in an internal subprogram is only visible to that subprogram; i.e. -
Subroutines – Get Efficient
Subroutines – get efficient So far: The code we have looked at so far has been sequential: Subroutines – getting efficient with Perl do this; do that; now do something; finish; Problem Bela Tiwari You need something to be done over and over, perhaps slightly [email protected] differently depending on the context Solution Environmental Genomics Thematic Programme Put the code in a subroutine and call the subroutine whenever needed. Data Centre http://envgen.nox.ac.uk Syntax: There are a number of correct ways you can define and use Subroutines – get efficient subroutines. One is: A subroutine is a named block of code that can be executed as many times #!/usr/bin/perl as you wish. some code here; some more here; An artificial example: lalala(); #declare and call the subroutine Instead of: a bit more code here; print “Hello everyone!”; exit(); #explicitly exit the program ############ You could use: sub lalala { #define the subroutine sub hello_sub { print "Hello everyone!\n“; } #subroutine definition code to define what lalala does; #code defining the functionality of lalala more defining lalala; &hello_sub; #call the subroutine return(); #end of subroutine – return to the program } Syntax: Outline review of previous slide: Subroutines – get efficient Syntax: #!/usr/bin/perl Permutations on the theme: lalala(); #call the subroutine Defining the whole subroutine within the script when it is first needed: sub hello_sub {print “Hello everyone\n”;} ########### sub lalala { #define the subroutine The use of an ampersand to call the subroutine: &hello_sub; return(); #end of subroutine – return to the program } Note: There are subtle differences in the syntax allowed and required by Perl depending on how you declare/define/call your subroutines. -
NUG Single Node Optimization Presentation
Single Node Optimization on Hopper Michael Stewart, NERSC Introduction ● Why are there so many compilers available on Hopper? ● Strengths and weaknesses of each compiler. ● Advice on choosing the most appropriate compiler for your work. ● Comparative benchmark results. ● How to compile and run with OpenMP for each compiler. ● Recommendations for running hybrid MPI/OpenMP codes on a node. Why So Many Compilers on Hopper? ● Franklin was delivered with the only commercially available compiler for Cray Opteron systems, PGI. ● GNU compilers were on Franklin, but at that time GNU Fortran optimization was poor. ● Next came Pathscale because of superior optimization. ● Cray was finally legally allowed to port their compiler to the Opteron so it was added next. ● Intel was popular on Carver, and it produced highly optimized codes on Hopper. ● PGI is still the default, but this is not a NERSC recommendation. Cray's current default is the Cray compiler, but we kept PGI to avoid disruption. PGI ● Strengths ○ Available on a wide variety of platforms making codes very portable. ○ Because of its wide usage, it is likely to compile almost any valid code cleanly. ● Weaknesses ○ Does not optimize as well as compilers more narrowly targeted to AMD architectures. ● Optimization recommendation: ○ -fast Cray ● Strengths ○ Fortran is well optimized for the Hopper architecture. ○ Uses Cray math libraries for optimization. ○ Well supported. ● Weaknesses ○ Compilations can take much longer than with other compilers. ○ Not very good optimization of C++ codes. ● Optimization recommendations: ○ Compile with no explicit optimization arguments. The default level of optimization is very high. Intel ● Strengths ○ Optimizes C++ and Fortran codes very well. -
PHYS-4007/5007: Computational Physics Course Lecture Notes Section II
PHYS-4007/5007: Computational Physics Course Lecture Notes Section II Dr. Donald G. Luttermoser East Tennessee State University Version 7.1 Abstract These class notes are designed for use of the instructor and students of the course PHYS-4007/5007: Computational Physics taught by Dr. Donald Luttermoser at East Tennessee State University. II. Choosing a Programming Language A. Which is the Best Programming Language for Your Work? 1. You have come up with a scientific idea which will require nu- merical work using a computer. One needs to ask oneself, which programming language will work best for the project? a) Projects involving data reduction and analysis typically need software with graphics capabilities. Examples of such graphics languages include IDL, Mathlab, Origin, GNU- plot, SuperMongo, and Mathematica. b) Projects involving a lot of ‘number-crunching’ typically require a programming language that is capable of car- rying out math functions in scientific notation with as much precision as possible. In physics and astronomy, the most commonly used number-crunching programming languages include the various flavors of Fortran, C, and more recently, Python. i) As noted in the last section, the decades old For- tran 77 is still widely use in physics and astronomy. ii) Over the past few years, Python has been growing in popularity in scientific programming. c) In this class, we will focus on two programming languages: Fortran and Python. From time to time we will discuss the IDL programming language since some of you may encounter this software during your graduate and profes- sional career. d) Any coding introduced in these notes will be written in either of these three programming languages. -
COBOL-Skills, Where Art Thou?
DEGREE PROJECT IN COMPUTER ENGINEERING 180 CREDITS, BASIC LEVEL STOCKHOLM, SWEDEN 2016 COBOL-skills, Where art Thou? An assessment of future COBOL needs at Handelsbanken Samy Khatib KTH ROYAL INSTITUTE OF TECHNOLOGY i INFORMATION AND COMMUNICATION TECHNOLOGY Abstract The impending mass retirement of baby-boomer COBOL developers, has companies that wish to maintain their COBOL systems fearing a skill shortage. Due to the dominance of COBOL within the financial sector, COBOL will be continually developed over at least the coming decade. This thesis consists of two parts. The first part consists of a literature study of COBOL; both as a programming language and the skills required as a COBOL developer. Interviews were conducted with key Handelsbanken staff, regarding the current state of COBOL and the future of COBOL in Handelsbanken. The second part consists of a quantitative forecast of future COBOL workforce state in Handelsbanken. The forecast uses data that was gathered by sending out a questionnaire to all COBOL staff. The continued lack of COBOL developers entering the labor market may create a skill-shortage. It is crucial to gather the knowledge of the skilled developers before they retire, as changes in old COBOL systems may have gone undocumented, making it very hard for new developers to understand how the systems work without guidance. To mitigate the skill shortage and enable modernization, an extraction of the business knowledge from the systems should be done. Doing this before the current COBOL workforce retires will ease the understanding of the extracted data. The forecasts of Handelsbanken’s COBOL workforce are based on developer experience and hiring, averaged over the last five years. -
Subroutines and Control Abstraction
Subroutines and Control Abstraction CSE 307 – Principles of Programming Languages Stony Brook University http://www.cs.stonybrook.edu/~cse307 1 Subroutines Why use subroutines? Give a name to a task. We no longer care how the task is done. The subroutine call is an expression Subroutines take arguments (in the formal parameters) Values are placed into variables (actual parameters/arguments), and A value is (usually) returned 2 (c) Paul Fodor (CS Stony Brook) and Elsevier Review Of Memory Layout Allocation strategies: Static Code Globals Explicit constants (including strings, sets, other aggregates) Small scalars may be stored in the instructions themselves Stack parameters local variables temporaries bookkeeping information Heap 3 dynamic allocation(c) Paul Fodor (CS Stony Brook) and Elsevier Review Of Stack Layout 4 (c) Paul Fodor (CS Stony Brook) and Elsevier Review Of Stack Layout Contents of a stack frame: bookkeeping return Program Counter saved registers line number static link arguments and returns local variables temporaries 5 (c) Paul Fodor (CS Stony Brook) and Elsevier Calling Sequences Maintenance of stack is responsibility of calling sequence and subroutines prolog and epilog Tasks that must be accomplished on the way into a subroutine include passing parameters, saving the return address, changing the program counter, changing the stack pointer to allocate space, saving registers (including the frame pointer) that contain important values and that may be overwritten by the callee, changing the frame pointer to refer to the new frame, and executing initialization code for any objects in the new frame that require it. Tasks that must be accomplished on the way out include passing return parameters or function values, executing finalization code for any local objects that require it, deallocating the stack frame (restoring the stack pointer), restoring other saved registers (including the frame pointer), and restoring the program counter. -
A Subroutine's Stack Frames Differently • May Require That the Steps Involved in Calling a Subroutine Be Performed in Different Orders
Chapter 04: Instruction Sets and the Processor organizations Lesson 14 Use of the Stack Frames Schaum’s Outline of Theory and Problems of Computer Architecture 1 Copyright © The McGraw-Hill Companies Inc. Indian Special Edition 2009 Objective • To understand call and return, nested calls and use of stack frames Schaum’s Outline of Theory and Problems of Computer Architecture 2 Copyright © The McGraw-Hill Companies Inc. Indian Special Edition 2009 Calling a subroutine Schaum’s Outline of Theory and Problems of Computer Architecture 3 Copyright © The McGraw-Hill Companies Inc. Indian Special Edition 2009 Calls to the subroutines • Allow commonly used functions to be written once and used whenever they are needed, and provide abstraction, making it easier for multiple programmers to collaborate on a program • Important part of virtually all computer languages • Function calls in a C language program • Also included additional functions from library by including the header files Schaum’s Outline of Theory and Problems of Computer Architecture 4 Copyright © The McGraw-Hill Companies Inc. Indian Special Edition 2009 Difficulties when Calling a subroutine Schaum’s Outline of Theory and Problems of Computer Architecture 5 Copyright © The McGraw-Hill Companies Inc. Indian Special Edition 2009 Difficulties involved in implementing subroutine calls 1. Programs need a way to pass inputs to subroutines that they call and to receive outputs back from them Schaum’s Outline of Theory and Problems of Computer Architecture 6 Copyright © The McGraw-Hill Companies Inc. Indian Special Edition 2009 Difficulties involved in implementing subroutine calls 2. Subroutines need to be able to allocate space in memory for local variables without overwriting any data used by the subroutine-calling program Schaum’s Outline of Theory and Problems of Computer Architecture 7 Copyright © The McGraw-Hill Companies Inc. -
Chapter 9: Functions and Subroutines – Reusing Code. Page 125 Chapter 9: Functions and Subroutines – Reusing Code
Chapter 9: Functions and Subroutines – Reusing Code. Page 125 Chapter 9: Functions and Subroutines – Reusing Code. This chapter introduces the use of Functions and Subroutines. Programmers create subroutines and functions to test small parts of a program, reuse these parts where they are needed, extend the programming language, and simplify programs. Functions: A function is a small program within your larger program that does something for you. You may send zero or more values to a function and the function will return one value. You are already familiar with several built in functions like: rand and rgb. Now we will create our own. Illustration 22: Block Diagram of a Function © 2014 James M. Reneau (CC BY-NC-SA 3.0 US) Chapter 9: Functions and Subroutines – Reusing Code. Page 126 Function functionname( argument(s) ) statements End Function Function functionname$( argument(s) ) statements End Function The Function statement creates a new named block of programming statements and assigns a unique name to that block of code. It is recommended that you do not name your function the same name as a variable in your program, as it may cause confusion later. In the required parenthesis you may also define a list of variables that will receive values from the “calling” part of the program. These variables belong to the function and are not available to the part of the program that calls the function. A function definition must be closed or finished with an End Function. This tells the computer that we are done defining the function. The value being returned by the function may be set in one of two ways: 1) by using the return statement with a value following it or 2) by setting the function name to a value within the function. -
Using GNU Fortran 95
Contributed by Steven Bosscher ([email protected]). Using GNU Fortran 95 Steven Bosscher For the 4.0.4 Version* Published by the Free Software Foundation 59 Temple Place - Suite 330 Boston, MA 02111-1307, USA Copyright c 1999-2005 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with the Invariant Sections being “GNU General Public License” and “Funding Free Software”, the Front-Cover texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in the section entitled “GNU Free Documentation License”. (a) The FSF’s Front-Cover Text is: A GNU Manual (b) The FSF’s Back-Cover Text is: You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development. i Short Contents Introduction ...................................... 1 GNU GENERAL PUBLIC LICENSE .................... 3 GNU Free Documentation License ....................... 9 Funding Free Software .............................. 17 1 Getting Started................................ 19 2 GFORTRAN and GCC .......................... 21 3 GFORTRAN and G77 ........................... 23 4 GNU Fortran 95 Command Options.................. 25 5 Project Status ................................ 33 6 Extensions ................................... 37 7 Intrinsic Procedures ............................ -
Object Oriented Programming*
SLAC-PUB-5629 August 1991 ESTABLISHED 1962 (T/E/I) Object Oriented Programming* Paul F. Kunz Stanford Linear Accelerator Center Stanford University Stanford, California 94309, USA ABSTRACT This paper is an introduction to object oriented programming. The object oriented approach is very pow- erful and not inherently difficult, but most programmers find a relatively high threshold in learning it. Thus, this paper will attempt to convey the concepts with examples rather than explain the formal theory. 1.0 Introduction program is a collection of interacting objects that commu- nicate with each other via messaging. To the FORTRAN In this paper, the object oriented programming tech- programmer, a message is like a CALL to a subroutine. In niques will be explored. We will try to understand what it object oriented programming, the message tells an object really is and how it works. Analogies will be made with tra- what operation should be performed on its data. The word ditional programming in an attempt to separate the basic method is used for the name of the operation to be carried concepts from the details of learning a new programming out. The last key idea is that of inheritance. This idea can language. Most experienced programmers find there is a not be explained until the other ideas are better understood, relatively high threshold in learning the object oriented thus it will be treated later on in this paper. techniques. There are a lot of new words for which one An object is executable code with local data. This data needs to know the meaning in the context of a program; is called instance variables.