C++ I/O Tips: Saving Huge Text File using Boost Library

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以前这篇文章写过利用Boost的内存映射来读取超大文件,但是读取的目的最终还是要写入结果文件.网络上使用Boost来读取文件的例子不少,但是写文件的例子则寥寥无几.记录一下,以备将来使用.

Tetrahedron Properties

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做CFD与FEA分析,经常要与网格打交道.而FEA分析最常用的网格大概就数四面体网格了(tetrahedron).无论是4-node还是10-node,其几何形状都是经典的三棱锥.本文记录一些用到的四面体属性知识.

C++ I/O Tips: Parsing Huge Text File

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问题提出

最近项目需要读取mesh文件,基本做过CFD的都知道,几千万Elements的mesh文件动辄几个Gb,庞大的体积让各种操作都很不方便.而获取数据需要与磁盘打交道,作为后续处理的第一步,是一切的开端.如果需要读取的文件是二进制格式,会有些帮助.但是不同的网格划分软件大都有其自有格式,等于是带着枷锁跳舞.

注意:这里的测试使用的都是文本文件,可能不适用于二进制文件读写.

下文使用的开发环境: VS2013 + Win10 + i7 CPU/16G Ram.
测试数据是ICEM导出的Star-CD的vrt格式.这种格式可以看作是文本文件,每一行一组数据表示一个Node(也就是一个三维点): Node_ID X Y Z.Mesh有多少个Node,文件就有多少行.

Get Matlab Version

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Matlab provides loads of useful functions for scientific computing. However, the functions might be added or deprecated from version to version. To write more robust codes, it's always a good practice to deal with different cases. An if...else... clause would be enough for this purpose.

Get the latest release folder from a directory

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Sometimes, we might need to find the latest release folder from a software repository according to the time stamp of the folder property. This could be done by extracting all the time stamps and sort them accordingly. MATLAB provides several function to do this nicely.

Scroll to the last line of text edit in Matlab

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Matlab's edit UIControl provide some flexibilities for displaying information, while setting the Max-Min>1 it supports multiple line. However, the caret is alwasy set to 0 position in the first line which is very annoy while you would like to show dynamic updated information to the user. To implement this capability, the underlying Java class has to be digged out. Yair M. Altman's findjobj.m function works perfectly to obtain those kind of information. Then, all we need to do is providing the Matlab UIControl's handle and set caret to the document length.