William Kahan and Joseph D. Darcy. How java's floating-point hurts everyone everywhere. In ACM 1998.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of distributed computing systems [9, 8, 2] An early exploration of Java support for Condor [19] examined primarily the problem of transparent checkpointing. One major obstacle to the acceptance of Java in scientific computing is a concern about the precise semantics of floating point operations [25]. 7. Conclusion We have used the Condor Java Universe as a detailed example for exploring a theory of error propagation. The main contributions of our theory are several succinct design principles and the concept of error scope. In summary, our principles are: 1. A program must not generate an ....

W. Kahan and J. Darcy. How Java's floating-point hurts everyone everywhere. Talk given at the ACM 1998.

....under testing. This report is organized as follows. Section 2 describes a direct search method for automatic error analysis proposed by Higham [2, Page 473] The e ectiveness of this method depends on the construction of an objective function. Section 3 introduces a debugging method by Kahan [4]. Like most automatic error analysis methods, this method requires the user to supply proper input data to reveal numerical instability. Our method, which requires neither the construction of an objective function nor proper input data, is presented in Section 4. Finally, Section 5 gives ....

....function (4) using backward error analysis. 3 Instability Detection The direct search method described in the previous section requires the construction of an objective function. In Example 1, the objective function (2) uses the exact results, which are unknown in most applications. Kahan [4] proposed a method for detecting instability 3 Rounding mode Heron s Formula Better Formula to nearest 12345680.0 6249012.0 to 1 12345680.0 6249013.0 to 1 0.0 6249011.0 to 0 0.0 6249011.0 Table 1: Area of the triangle with side lengths a = 12345679, b = 12345679, and c = 1:01233995 computed ....

W. Kahan and Joseph D. Darcy. How Java's Floating-Point Hurts Everyone Everywhere, 1998. URL=http://www.cs.berkeley.edu/wkahan/JAVAhurt.pdf 9

....good, performance relative to what might be obtained by programming closer to the machine may not be achievable within a Java only environment. 2. 2 Numerics Java is not suitable for doing precise scientific computations due to its present lack of support for the IEEE floating point standard [14]. This means that numerical calculations which require a certain level of floating point accuracy and consistency cannot be guaranteed to possess such characteristics across all JVM implementations. This poses a fundamental problem for many codes. 2.3 Bandwidth Java Remote Method Invocation ....

.... be re written in Java, in order to take advantage of the object oriented paradigm and the Java platform features [6] Unfortunately, direct support for complex types and an easy to use syntax for multi dimensional arrays are not currently available as part of the core Java language platform [14]. Furthermore, a significant amount of time and effort has been spent on getting existing scientific codes to work efficiently and reliably on specific platforms. Hence, there will be a reluctance to port existing codes to Java. 3 Middle Ground Given the preceding points, Java seems ill suited ....

Kahan, W., and Darcy, J. How JAVA's FloatingPoint Hurts Everyone Everywhere, March 1998. http://www.cs.berkeley.edu/ wkahan/JAVAhurt.pdf.

....UK z Contact author: gray math.uni.edu x Department of Mathematics, University of Northern Iowa, Cedar Falls, IA 50614 Department of Mathematics and Computer Science, Emory University, Atlanta, GA 30322 programming language. These issues have been discussed at length, for example, in [4] [18] and [16] respectively. During the evolutionary period of the Java programming language, other independent projects have evolved that have taken on the task of extending the de nition of a computational environment, such as Globus [3] and Legion [14] These metacomputing environments share a ....

W.Kahan, and Darcy, J. How Java's Floating-point Hurts Everyone Everywhere. Presentation at the ACM Workshop on Java for High-Network Computing, Mar. 1998. document available at www.cs.berkeley.edu/wkahan/JAVAHurt.pdf. 17

....present lack of acceptance of an IEEE floating point standard, and the abundance of legacy code are some of the reasons for reluctance of the scientific community to completely accept Java as a high performance programming language. These issues have been discussed at length, for example, in [2] [13] and [10] respectively. While optimized programs written in native languages such as C or Fortran still maintain a significant performance advantage over just in time (jit) execution of Java code, they can not exhibit the degree of portability attributable to Java programs through Java s ....

W.Kahan, and Darcy, J. How Java's Floating-point Hurts Everyone Everywhere. Presentation at the ACM Workshop on Java for High-Network Computing, Mar. 1998. document available at www.cs.berkeley.edu/¸wkahan/JAVAHurt.pdf.

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W. Kahan and J. D. Darcy. How Java's Floating-Point Hurts Everyone Everywhere. http://www.cs.berkeley.edu/wkahan/JAVAhurt.pdf, 1998.

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W. Kahan and J. D. Darcy. How Java's Floating-Point Hurts Everyone Everywhere. http://www.cs.berkeley.edu/wkahan/JAVAhurt.pdf, 1998.

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W. Kahan and J. D. Darcy. How Java's Floating-Point Hurts Everyone Everywhere. http://www.cs.berkeley.edu/#wkahan/JAVAhurt.pdf, 1998. 56

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William Kahan and Joseph D. Darcy. How java's floating-point hurts everyone everywhere. In ACM 1998.

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