<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[gotofly21的专栏]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/gotofly21</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; gotofly21]]></copyright><item><title><![CDATA[判断点是否在圆弧上]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/133739807</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/133739807</guid><author>gotofly21</author><pubDate>Tue, 10 Oct 2023 10:04:12 +0800</pubDate><description><![CDATA[首先用到圆心的距离判断是否在圆上. 不是 返回 false。再根据顺圆还是逆圆 判断 是否在圆上。判断是不是整圆 是 返回 true。]]></description><category></category></item><item><title><![CDATA[一种双向选择排序]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/124796386</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/124796386</guid><author>gotofly21</author><pubDate>Mon, 16 May 2022 11:31:49 +0800</pubDate><description><![CDATA[在选择排序基础上,增加尾部选择,形成前面选小的,后面选大的,大大提高了效率]]></description><category></category></item><item><title><![CDATA[毕业多年,终于明白啥是卷积了.]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/105503501</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/105503501</guid><author>gotofly21</author><pubDate>Tue, 14 Apr 2020 08:21:03 +0800</pubDate><description><![CDATA[int conv(int x)
{
 int X_delay[4];
 static int H[4]={1,1,1,1};
 int i,y;
 for(i=3;i&gt;0;i--)
 {
 X_delay[i] = X_delay[i-1];//这就是所谓延时器,

                     //X_delay[1]是...]]></description><category></category></item><item><title><![CDATA[while 动作 redo 化]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/105284819</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/105284819</guid><author>gotofly21</author><pubDate>Fri, 03 Apr 2020 08:47:33 +0800</pubDate><description><![CDATA[#ifndef _ReDo_H_
#define _ReDo_H_

#define REDO_1(ACT)   do{ ACT; }while(0)
#define REDO_2(ACT)   do{ REDO_1(ACT);REDO_1(ACT); }while(0)
#define REDO_3(ACT)   do{ REDO_2(ACT);REDO_1(ACT); }while(0)...]]></description><category></category></item><item><title><![CDATA[矩阵转置]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/105192212</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/105192212</guid><author>gotofly21</author><pubDate>Mon, 30 Mar 2020 09:38:26 +0800</pubDate><description><![CDATA[#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;

typedef struct
{
double *datap;
int lie; //列
int hang;//行
}Dmatrix_t;

int Dmatrix_Trans(Dmatrix_t *D_p,Dmatrix_t *S_p)
{
 if(D_p-&gt;hang != S...]]></description><category></category></item><item><title><![CDATA[大小端转换函数htonl(),htons(),ntohl(),ntons() 重写]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/105120240</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/105120240</guid><author>gotofly21</author><pubDate>Thu, 26 Mar 2020 15:44:19 +0800</pubDate><description><![CDATA[unsigned inthtonl(unsigned int x)

{

unsigned int y;

 ((unsigned char*)&amp;y)[0]= ((unsigned char*)&amp;x)[3];
 ((unsigned char*)&amp;y)[1]= ((unsigned char*)&amp;x)[2];
 ((unsigned c...]]></description><category></category></item><item><title><![CDATA[矩阵求逆]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/82413765</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/82413765</guid><author>gotofly21</author><pubDate>Wed, 05 Sep 2018 08:14:07 +0800</pubDate><description><![CDATA[// X 原  Y输出  Z余子式临时空间
int  DMatrix_Rev( Dmatrix_t *X, Dmatrix_t *Y, Dmatrix_t *Z  )
{
    double val,val_z,*Xp,*Yp,*Zp;
    int i,j,m,n,k,k_ou;
    if(X-&amp;gt;hang!= X-&amp;gt;lie ) return 0;
    if(X-&amp;gt;h...]]></description><category></category></item><item><title><![CDATA[矩阵求值]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/82386126</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/82386126</guid><author>gotofly21</author><pubDate>Tue, 04 Sep 2018 16:46:12 +0800</pubDate><description><![CDATA[typedef struct 
{
  double *datap;
  int    lie;//列
  int    hang;//
}Dmatrix_t;


__inline double *DMatrix_ij_P(Dmatrix_t *X,int i,int j )
{
    return ( X-&amp;gt;datap+ i*X-&amp;gt;lie+ j);    
}
int DMatr...]]></description><category></category></item><item><title><![CDATA[矩阵乘法]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/82257808</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/82257808</guid><author>gotofly21</author><pubDate>Fri, 31 Aug 2018 16:04:24 +0800</pubDate><description><![CDATA[typedef struct 
{
  double *datap;
  int    lie;//列
  int    hang;//
}Dmatrix_t;

 

int DMatrix_mul(Dmatrix_t *X,Dmatrix_t *Y,Dmatrix_t *Z)// z=A*B
{
   int i=0,j=0,k=0;
   double  *Z_p,*X_p,*Y_p;
  ...]]></description><category></category></item><item><title><![CDATA[字库缓冲]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/82215777</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/82215777</guid><author>gotofly21</author><pubDate>Thu, 30 Aug 2018 09:07:42 +0800</pubDate><description><![CDATA[做一个项目，很多页面显示的汉字大同小异。字库存在外部flash，stm32 ram很大用不完，本着反正闲着也是闲着，做了一个缓冲区减少读取字库次数，效果有点，原来拉窗明显，现在几乎没有。算法很粗糙。

#define BYTES_PER_FONT 144   //最大支持32*32的汉字

static uint8_t GUI_FontDataBuf[BYTES_PER_FONT];

//字库缓...]]></description><category></category></item><item><title><![CDATA[浮点数比较]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/82215457</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/82215457</guid><author>gotofly21</author><pubDate>Thu, 30 Aug 2018 08:36:45 +0800</pubDate><description><![CDATA[由于计算机中浮点数并不是精确表示，所以两个浮点数不能直接比较，而是要在一个误差范围内比较。

有的文章还要用相对误差比较。我用到地方都只需要绝对误差比较就行了。绝对误差 eps=1e-8

#define  eps 1e-8
#pragma inline=forced
 int double_cmp_biger( double data1,double data2 )
{
 return (int...]]></description><category></category></item><item><title><![CDATA[在IAR的集成开发环境中实现数据变量定位方法如下三种]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/41861953</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/41861953</guid><author>gotofly21</author><pubDate>Thu, 11 Dec 2014 08:03:08 +0800</pubDate><description><![CDATA[在IAR的集成开发环境中实现数据变量定位方法如下三种
1、__no_init char alpha @ 0x0200;

2、#pragma location = 0x0202
const int beta;

3、const int gamma @ 0x0204 = 3;

或：
1）__no_init int alpha @ "MYSEGMENT"; //MYSEGMENT段]]></description><category></category></item><item><title><![CDATA[mathmatic求两圆交点]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/41010693</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/41010693</guid><author>gotofly21</author><pubDate>Tue, 11 Nov 2014 14:16:12 +0800</pubDate><description><![CDATA[用
求两圆的交点，Solve[(x - a1)*(b2 - b1) == (y - b1)*(a2 - a1) && (x - c1)*(d2 - 
                                           d1) == (y - d1)*(c2 - c1), {x, y}]]]></description><category></category></item><item><title><![CDATA[自创字符串查找方法]]></title><link>https://blog.youkuaiyun.com/gotofly21/article/details/40391891</link><guid>https://blog.youkuaiyun.com/gotofly21/article/details/40391891</guid><author>gotofly21</author><pubDate>Thu, 23 Oct 2014 09:52:23 +0800</pubDate><description><![CDATA[kmp  bm  Sunday 方法说白了都要字符串比较，这一步都很费时间，有没有略去或者至少件事这减少这一步骤度呢。
考虑目标字符串   str1=“abcd”，我们把他加起来 sum1=‘a’+'b'+‘c’+'d';
str2="a1b2c3abc2abcd";我们也4个字符加起来，如果不相等后移一位再求和比较，如果相等，再用字符串比较，字符串不等再后移。
这不是脱裤子放屁吗。还多一步]]></description><category></category></item></channel></rss>