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Questions tagged [c]

C is a general purpose programming language. Originally intended for implementing system software, C and its close relatives are the principle languages used in most modern operating systems. Due to its thin layer of abstraction and low overhead, C allows efficient coding of algorithms and data structures useful for scientific computation. Use this tag for questions involving the C programming language.

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9
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3answers
3k views

How do I know if my code is being vectorized by the compiler?

As exemplified by Jed Brown's answer to Costs of lookups versus calculations, using vectorized vs non-vectorized floating point operations results in much faster code. Many modern compilers claim ...
13
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4answers
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Is C slower than Fortran on the spectral norm shootout (using gcc, intel and other compilers)?

The conclusion here: How much better are Fortran compilers really? is that gfortran and gcc are as fast for simple code. So I wanted try something more complicated. I took the spectral norm shootout ...
2
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1answer
559 views

Implicitly casting PetscReal to the real part of PetscComplex

The version of Petsc installed on my machine has PetscScalar set to be complex. I am making a matrix which has all real entries. Something like the following code compiles: ...
15
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3answers
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I/O Strategies for computational problems with large data sets?

My research group focuses on molecular dynamics, which obviously can generate gigabytes of data as part of a single trajectory which must then be analyzed. Several of the problems we're concerned ...
13
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1answer
336 views

Is there a tool out there that can generate interval extensions of Fortran (or C) functions by parsing Fortran (or C) code?

Case studies in my PhD thesis require that I have interval extensions of Fortran subroutines in CHEMKIN-II (apologies for the link; it's the best one I could find for a package no longer distributed ...
4
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3answers
433 views

How to obtain finite difference, which is continuous

I want to calculate a finite difference (something like this SO Post). My data is as follows: I have x-values that are powers of two (4, 8, 16, 32 and 64). Corresponding to them are y-values, such ...
75
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6answers
17k views

How much better are Fortran compilers really?

This question is an extension of two discussions that came up recently in the replies to "C++ vs Fortran for HPC". And it is a bit more of a challenge than a question... One of the most often-heard ...
6
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2answers
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Which libraries have good implementations of Basis splines?

I'm looking to use the finite element method with B-splines as my function basis. Which C/C++ libraries have good B-spline support? Specifically, I'm looking for an implementation of a stable ...
4
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1answer
510 views

PETSc's makefile system can't find MKL

I'm learning PETSc and trying to make the examples written in C. However, when I use the provided makefile, I get the following error: ...
54
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17answers
3k views

Is it common not to use libraries for standard numerical algorithms, and why?

A lot of numerical algorithms (integration, differentiation, interpolation, special functions, etc.) are available in scientific computation libraries like GSL. But I often see code with "hand-rolled" ...
12
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2answers
2k views

Is there an open source set of ODE solvers for C that use the native C99 complex type?

I've been using GSL as the foundation of many of my simulations, but it's a little bit overkill for my purposes and it defines its own complex type for legacy reasons. Rather than code my own Runge-...
17
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8answers
2k views

Parsing protein structure data in C

My background is in genomics, but I have recently been working with problems related to protein structure. I wrote a few relevant programs in C, building my own PDB file parser from scratch in the ...