Michael Metcalf

Fortran 90 explained

Whither fortran? language elements expressions and assignments control statements program units and procedures array features specification statements intrinsic procedures data transfer operations on external files depracated features.

Tomographic Measurements of Longitudinal Phase Space Density

Abstract Tomography — the reconstruction of a two-dimensional image from a series of its one-dimensional projections — is now a very broad topic with a wealth of algorithms for the reconstructions of both qualitative and quantitative images. One of the simplest algorithms has been modified to take into account the nonlinearity of large-amplitude synchrotron motion in a particle accelerator. This permits the accurate reconstruction of longitudinal phase space density from one-dimensional bunch profile data. The algorithm was developed in Mathematica™ in order to exploit the extensive built-in functions and graphics. Subsequently, it has been recoded in Fortran 90 with the aim of reducing the execution time by at least a factor of one hundred. The choice of Fortran 90 was governed by the desire ultimately to exploit parallel architectures, but sequential compilation and execution have already largely yielded the required gain in speed. The use of the method to produce longitudinal phase space plots, animated sequences of the evolution of phase space density and to estimate accelerator parameters is presented. More generally, the new algorithm constitutes an extension of computerized tomography which carers for nonrigid bodies whose projections cannot be measured simultaneously.

The seven ages of Fortran

When IBMs John Backus first developed the Fortran programming language, back in 1957, he certainly never dreamt that it would become a world-wide success and still be going strong many years later. Given the oft-repeated predictions of its imminent demise, starting around 1968, it is a surprise, even to some of its most devoted users, that this much-maligned language is not only still with us, but is being further developed for the demanding applications of the future. What has made this programming language succeed where most slip into oblivion? One reason is certainly that the language has been regularly standardized. In this paper we will trace the evolution of the language from its first version and though six cycles of formal revision, and speculate on how this might continue. Now, modern Fortran is a procedural, imperative, compiled language with a syntax well suited to a direct representation of mathematical formulas. Individual procedures may be compiled separately or grouped into modules, either way allowing the convenient construction of very large programs and procedure libraries. Procedures communicate via global data areas or by argument association. The language now contains features for array processing, abstract data types, dynamic data structures, objectoriented programming and parallel processing.An advanced geometric modeler GEMS4.0 has been developed, in which feature representation is used at the highest level abstraction of a product model. Boundary representation is used at the bottom level, while CSG model is adopted at the median level. A BRep data structure capable of modeling non-manifold is adopted. NURBS representation is used for all curved surfaces. Quadric surfaces have dual representations consisting of their geometric data such as radius, center point, and center axis. Boundary representation of free form surfaces is easily built by sweeping and skinning method with NURBS geometry. Set operations on curved solids with boundary representation are performed by an evaluation process consisting of four steps. A file exchange facility is provided for the conversion between product data described by STEP and product information generated by GEMS4.0.

Has Fortran a future

Abstract For over 25 years FORTRAN has dominated all other programming languages in the field of scientific and engineering computation. Although much denigrated by computer-science purists, it has consistently shown itself to be attractive to scientific users because its basic simplicitly and power of expression appeal to non-specialists. Can this situation continue? Will the introduction of FORTRAN 77 lead to an upsurge in the use of the language, providing it with momentum sufficient to carry it through to the end of the decade? Shall we witness a conflict between FORTRAN 8x and ADA? This lecture will take stock of the present status of FORTRAN and describe its likely development, before going on to speculate on possible trends until the turn of the century.

Fortran 8x — The emerging standard

Abstract Since 1979, the Fortran standardization committee, X3J3, has been labouring over a draft for the next version of the standard. Its initial intention of publishing this draft in 1982 was hopelessly optimistic, and at best it may be ready this year. However, a number of fundamental issues have been thrown up over the past two years, such that it is clear that unanimity cannot be achieved: efficiency versus functionality; safety versus obsolescence; small and simple or big and powerful? This paper reviews the current state and content of Fortran 8x, and attempts to bring out some of the controversial issues surrounding its development.

A first encounter with f90

A few weeks before the formal publication of the International Fortran 90 Standard, the worlds first Fortran 90 compiler (f90) was announced. CERN was invited to perform beta-testing, and the opportunity was taken subsequently to assess the impact of Fortran 90 on the CERN Program Library.

Fortran 77 coding conventions

In this note we follow the scheme of Vapne [Ref. 1], classifying each point according to its position in the language and its relevance, either to portability or to programming style. <u>Points marked with two asterisks should be regarded as mandatory for readable, portable code</u>, one asterisk indicates that the point is important, and unmarked points are to be considered only as desirable.

A Sudoku program in Fortran 95

A remarkable craze swept though many countries in the year 2005. Already known and popular in Japan, sudoku was introduced into the UK and thence into other European countries and the USA. Its rules are simple. Given a 9 x 9 grid with some numbers already in place, the solver has to fill in the missing values such that, in each row, each column and each 3 x 3 box, the digits 1 to 9 appear once and once only. The starting digits in this example are arranged symmetrically, which is merely a matter of taste. However, it is widely accepted that a properly formed puzzle has a unique solution and that it can thus be solved, without having to make any guesses, by pure logic.An excellent source of further details is the Wikipedia article at http://en.wikipedia.org/wiki/Sudoku

A derived‐data type for data analysis

A frequent requirement in physics data analysis is the ability to form and manipulate histograms; this is done currently using calls to the HBOOK subroutine package. Could its interfaces and internal structure be improved by defining a histogram to be a Fortran 90 data type instead?

Fortran 8X—the emerging standard

Since 1979, the Fortran standardization committee, X3J3, has been labouring over a draft for the next version of the standard. Its initial intention of publishing this draft in 1982 was hopelessly optimistic, and at best it may be ready this year. However, a number of fundamental issues have been thrown up over the past two years, such that it is clear that unanimity cannot be achieved: efficiency versus functionality; safety versus obsolescence; small and simple or big and powerful?This paper reviews the current state and content of Fortran 8x, and attempts to bring out some of the controversial issues surrounding its development.