我不时地读到Fortran在繁重的计算中比C更快。这是真的吗?我必须承认我几乎不懂Fortran,但是到目前为止我看到的Fortran代码并没有显示出该语言具有C语言所不具备的特性。

如果是真的,请告诉我原因。请不要告诉我什么语言或库适合处理数字,我不打算写一个应用程序或库来做这个,我只是好奇。


当前回答

This is more than somewhat subjective, because it gets into the quality of compilers and such more than anything else. However, to more directly answer your question, speaking from a language/compiler standpoint there is nothing about Fortran over C that is going to make it inherently faster or better than C. If you are doing heavy math operations, it will come down to the quality of the compiler, the skill of the programmer in each language and the intrinsic math support libraries that support those operations to ultimately determine which is going to be faster for a given implementation.

编辑:@Nils等人提出了一个很好的观点,即C语言中指针使用的差异,以及可能存在的别名,这可能会使C语言中最简单的实现变慢。然而,在C99中有一些方法可以解决这个问题,比如通过编译器优化标志和/或C语言的实际编写方式。这在@Nils的回答和随后的评论中有很好的介绍。

其他回答

Fortran traditionally doesn't set options such as -fp:strict (which ifort requires to enable some of the features in USE IEEE_arithmetic, a part of f2003 standard). Intel C++ also doesn't set -fp:strict as a default, but that is required for ERRNO handling, for example, and other C++ compilers don't make it convenient to turn off ERRNO or gain optimizations such as simd reduction. gcc and g++ have required me to set up Makefile to avoid using the dangerous combination -O3 -ffast-math -fopenmp -march=native. Other than these issues, this question about relative performance gets more nit-picky and dependent on local rules about choice of compilers and options.

没有一种语言比另一种语言更快,所以正确的答案是否定的。

你真正要问的是“用Fortran编译器X编译的代码是否比用C编译器Y编译的等效代码更快?”这个问题的答案当然取决于您选择哪两个编译器。

人们可能会问的另一个问题是“考虑到在他们的编译器中优化投入了相同的精力,哪个编译器会生成更快的代码?” 这个问题的答案实际上是Fortran。Fortran编译器有一些优势:

Fortran had to compete with Assembly back in the day when some vowed never to use compilers, so it was designed for speed. C was designed to be flexible. Fortran's niche has been number crunching. In this domain code is never fast enough. So there's always been a lot of pressure to keep the language efficient. Most of the research in compiler optimizations is done by people interested in speeding up Fortran number crunching code, so optimizing Fortran code is a much better known problem than optimizing any other compiled language, and new innovations show up in Fortran compilers first. Biggie: C encourages much more pointer use than Fortran. This drasticly increases the potential scope of any data item in a C program, which makes them far harder to optimize. Note that Ada is also way better than C in this realm, and is a much more modern OO Language than the commonly found Fortran77. If you want an OO langauge that can generate faster code than C, this is an option for you. Due again to its number-crunching niche, the customers of Fortran compilers tend to care more about optimization than the customers of C compilers.

然而,没有什么能阻止人们在C编译器的优化上投入大量精力,并使其生成比他们平台的Fortran编译器更好的代码。事实上,C编译器产生的较大销售额使得这种情况非常可行

Fortran和C之间的速度差异更多的是编译器优化和特定编译器使用的底层数学库的函数。Fortran没有什么固有的特性可以使它比C更快。

不管怎样,一个优秀的程序员可以用任何语言编写Fortran。

大多数帖子已经提出了令人信服的论点,所以我只是在另一个方面加上众所周知的2美分。

在处理能力方面,fortran更快或更慢是有其重要性的,但如果用fortran开发一些东西需要5倍多的时间,因为:

it lacks any good library for tasks different from pure number crunching it lack any decent tool for documentation and unit testing it's a language with very low expressivity, skyrocketing the number of lines of code. it has a very poor handling of strings it has an inane amount of issues among different compilers and architectures driving you crazy. it has a very poor IO strategy (READ/WRITE of sequential files. Yes, random access files exist but did you ever see them used?) it does not encourage good development practices, modularization. effective lack of a fully standard, fully compliant opensource compiler (both gfortran and g95 do not support everything) very poor interoperability with C (mangling: one underscore, two underscores, no underscore, in general one underscore but two if there's another underscore. and just let not delve into COMMON blocks...)

那么这个问题就无关紧要了。如果某样东西很慢,大多数时候你无法在给定的限制范围内改进它。如果你想要更快,改变算法。最后,使用电脑的时间很便宜。人类的时间不是。珍惜减少人类时间的选择。如果它增加了使用电脑的时间,无论如何它都是有成本效益的。

有趣的是,这里的很多答案都来自于不懂语言。这对于那些打开过旧的FORTRAN 77代码并讨论过其弱点的C/ c++程序员来说尤其如此。

我认为速度问题主要是C/ c++和Fortran之间的问题。在大型代码中,它总是取决于程序员。有一些语言特性是Fortran优于的,而一些特性是C优于的。所以,在2011年,没有人能真正说出哪一个更快。

About the language itself, Fortran nowadays supports Full OOP features and it is fully backward compatible. I have used the Fortran 2003 thoroughly and I would say it was just delightful to use it. In some aspects, Fortran 2003 is still behind C++ but let's look at the usage. Fortran is mostly used for Numerical Computation, and nobody uses fancy C++ OOP features because of speed reasons. In high performance computing, C++ has almost no place to go(have a look at the MPI standard and you'll see that C++ has been deprecated!).

现在,您可以简单地使用Fortran和C/ c++进行混合语言编程。Fortran中甚至有GTK+的接口。有免费的编译器(gfortran, g95)和许多优秀的商业编译器。