optimization

问题 I write a function to show images on a folder (assume i have about 60 images in this folder) in window phone 8.1. And the problem is function GetThumbnailAsync() take so long time when i create stream to get bitmapImage. Here's my code //getFileInPicture is function get all file in picture folder List<StorageFile> lstPicture = await getFileInPicture(); foreach (var file in lstPicture) { var thumbnail = await file.GetThumbnailAsync(Windows.Storage.FileProperties.ThumbnailMode.PicturesView,50);

问题 I have an application that queries and updates two databases at the same time (different from each other) and it has already around 10 to 15 years of usage. So I would like to start clearing up the garbage from them. One of the things that I want to do is to remove all the stored procedures that are in database B that by mistake were created there (because they had to go in database A). If I do one by one, is easy because I can tell if the sp uses a table that is not in that database. But I

问题 I have a CSV file 1.6 GB large, that I need to feed into matlab. I will have to do this frequently and I need it to run quickly. The file is of the form: 20111205 00:00.2 99.18 6 E 20111205 00:00.2 99.18 5 E 20111205 00:00.2 99.18 1 E 20111205 00:00.2 99.195 5 E 20111205 00:00.2 99.195 5 E 20111205 01:27.0 99.19 5 E 20111205 02:01.4 99.185 1 E 20111205 02:01.4 99.185 1 E 20111205 02:01.4 99.185 1 E 20111205 02:01.4 99.185 1 E The code I have right now is the following: tic; format long g fid

问题 I have a CSV file 1.6 GB large, that I need to feed into matlab. I will have to do this frequently and I need it to run quickly. The file is of the form: 20111205 00:00.2 99.18 6 E 20111205 00:00.2 99.18 5 E 20111205 00:00.2 99.18 1 E 20111205 00:00.2 99.195 5 E 20111205 00:00.2 99.195 5 E 20111205 01:27.0 99.19 5 E 20111205 02:01.4 99.185 1 E 20111205 02:01.4 99.185 1 E 20111205 02:01.4 99.185 1 E 20111205 02:01.4 99.185 1 E The code I have right now is the following: tic; format long g fid

问题 I have two matrices of interest, the first is a "bag of words" matrix, with two columns: the document ID and the term ID. For example: bow[0:10] Out[1]: array([[ 0, 10], [ 0, 12], [ 0, 19], [ 0, 20], [ 1, 9], [ 1, 24], [ 2, 33], [ 2, 34], [ 2, 35], [ 3, 2]]) In addition, I have an "index" matrix, where every row in the matrix contains the index of the first and last row for a given document ID in the bag of words matrix. Ex: row 0 is the first and last index for doc id 0. For example: index[0

问题 I have two matrices of interest, the first is a "bag of words" matrix, with two columns: the document ID and the term ID. For example: bow[0:10] Out[1]: array([[ 0, 10], [ 0, 12], [ 0, 19], [ 0, 20], [ 1, 9], [ 1, 24], [ 2, 33], [ 2, 34], [ 2, 35], [ 3, 2]]) In addition, I have an "index" matrix, where every row in the matrix contains the index of the first and last row for a given document ID in the bag of words matrix. Ex: row 0 is the first and last index for doc id 0. For example: index[0

问题 Consider the following method in Java: public static boolean expensiveComputation() { for (int i = 0; i < Integer.MAX_VALUE; ++i); return false; } And the following main method: public static void main(String[] args) { boolean b = false; if (expensiveComputation() && b) { } } Logical conjunction (same as &&) is a commutative operation. So why the compiler doesn't optimize the if-statement code to the equivalent: if (b && expensiveComputation()) { } which has the benefits of using short

问题 Hi I'm implementing some fixed point math stuff for embedded systems and I'm trying to do the multiplication of two 16.16 fixed point numbers without creating a 64bit temporary. So far here is the code I came up with that generates the least instructions. int multiply(int x, int y){ int result; long long temp = x; temp *= y; temp >>= 16; result = temp; return result; } the problem with this code is that it uses a temporary 64 bit integer which seem to generate bad assembly code. I'm trying to

问题 At the Velocity 2010 conference, Google said that header compression can yield big gains: Hölzle noted a glaring inefficiency in the handling of web page headers, which provide information about a user’s IP address, browser and other session data. The average web page makes 44 calls to different resources, with many of those requests including repetitive header data. Holzle said compressing the headers produces an 88 percent page load improvement for some leading sites. How does one ensure

问题 Starting with code like this void lib_memset( unsigned char *dest, unsigned char c, unsigned int n) { while(n--) { *dest=c; dest++; } } using llvm as a cross compiler clang -Wall -m32 -emit-llvm -fno-builtin --target=arm-none-eabi -c lib_memset.c -o lib_memset.bc opt -std-compile-opts -strip-debug -march=arm -mcpu=mpcore -mtriple=arm-none-eabi lib_memset.bc -o lib_memset.opt.bc llc -march=arm -mcpu=mpcore -disable-simplify-libcalls lib_memset.opt.bc -o lib_memset.opt.s llc -march=arm -mcpu