巧用数学函数生成函数表

在嵌入式的图像设计，数据加密，信号控制过程中，我们常常要用到数学用表来计算和处理数据。再也没有比刚有个好IDEA，代码写到中途时，却遇到一些需要查表的数据处理更难受的了，有时往往又在百度中找不到相应的数据。其实巧用数学函数，完全可以搞定大部分数据处理。由于嵌入式的特殊性，决定了我们为了效率等各方面考虑，不可能为之设计十分复杂的数学运算，优化算法只能查表，而手动输入或者CPAY都又易于出错，所以对于程序员来说，能用编程实现的问题都不是大问题。

 

#include "stdlib.h"#include "stdio.h"#include "math.h"#define PI 3.1415926#define STARTANG (270)#define GAPANG (1)#define LETOUT (1)void main(void){printf("sine = {/n");for (int i = 0+STARTANG; i < 360+270; i=i+GAPANG){if ((i % 5 == 0) && (i != 0)){printf("/n");}printf("%lf,/t", cos((PI*i)/180)*LETOUT);}printf("/n};/n");//printf("sin%d = %lf, cos%d = %lf, sqrt%d = %lf/n", i, sin((3.1415926*i)/180), i, cos((3.1415926*i)/180), i, sqrt(i));} 

上面的代码可以把需要的数据生成数组以供调用，PI可以调整精确度，STARTANG可以调整起始值，GAPANG可以调整表的间隔，LETOUT 可以放大生成的小浮点数，简化运算，cos 可以使用sqrt,sin,tan替换生成相应的表。

生成代码如下：

sine = {-0.000000,0.017452,0.034899,0.052336,0.069756,0.087156,0.104528,0.121869,0.139173,0.156434,0.173648,0.190809,0.207912,0.224951,0.241922,0.258819,0.275637,0.292372,0.309017,0.325568,0.342020,0.358368,0.374607,0.390731,0.406737,0.422618,0.438371,0.453990,0.469471,0.484810,0.500000,0.515038,0.529919,0.544639,0.559193,0.573576,0.587785,0.601815,0.615661,0.629320,0.642788,0.656059,0.669131,0.681998,0.694658,0.707107,0.719340,0.731354,0.743145,0.754710,0.766044,0.777146,0.788011,0.798635,0.809017,0.819152,0.829038,0.838671,0.848048,0.857167,0.866025,0.874620,0.882948,0.891006,0.898794,0.906308,0.913545,0.920505,0.927184,0.933580,0.939693,0.945519,0.951056,0.956305,0.961262,0.965926,0.970296,0.974370,0.978148,0.981627,0.984808,0.987688,0.990268,0.992546,0.994522,0.996195,0.997564,0.998630,0.999391,0.999848,1.000000,0.999848,0.999391,0.998630,0.997564,0.996195,0.994522,0.992546,0.990268,0.987688,0.984808,0.981627,0.978148,0.974370,0.970296,0.965926,0.961262,0.956305,0.951057,0.945519,0.939693,0.933580,0.927184,0.920505,0.913546,0.906308,0.898794,0.891007,0.882948,0.874620,0.866025,0.857167,0.848048,0.838671,0.829038,0.819152,0.809017,0.798636,0.788011,0.777146,0.766045,0.754710,0.743145,0.731354,0.719340,0.707107,0.694658,0.681998,0.669131,0.656059,0.642788,0.629320,0.615662,0.601815,0.587785,0.573577,0.559193,0.544639,0.529919,0.515038,0.500000,0.484810,0.469472,0.453991,0.438371,0.422618,0.406737,0.390731,0.374607,0.358368,0.342020,0.325568,0.309017,0.292372,0.275637,0.258819,0.241922,0.224951,0.207912,0.190809,0.173648,0.156435,0.139173,0.121869,0.104529,0.087156,0.069757,0.052336,0.034900,0.017453,0.000000,-0.017452,-0.034899,-0.052336,-0.069756,-0.087156,-0.104528,-0.121869,-0.139173,-0.156434,-0.173648,-0.190809,-0.207912,-0.224951,-0.241922,-0.258819,-0.275637,-0.292372,-0.309017,-0.325568,-0.342020,-0.358368,-0.374606,-0.390731,-0.406737,-0.422618,-0.438371,-0.453990,-0.469471,-0.484809,-0.500000,-0.515038,-0.529919,-0.544639,-0.559193,-0.573576,-0.587785,-0.601815,-0.615661,-0.629320,-0.642787,-0.656059,-0.669130,-0.681998,-0.694658,-0.707107,-0.719340,-0.731354,-0.743145,-0.754709,-0.766044,-0.777146,-0.788011,-0.798635,-0.809017,-0.819152,-0.829037,-0.838670,-0.848048,-0.857167,-0.866025,-0.874620,-0.882948,-0.891006,-0.898794,-0.906308,-0.913545,-0.920505,-0.927184,-0.933580,-0.939693,-0.945519,-0.951056,-0.956305,-0.961262,-0.965926,-0.970296,-0.974370,-0.978148,-0.981627,-0.984808,-0.987688,-0.990268,-0.992546,-0.994522,-0.996195,-0.997564,-0.998630,-0.999391,-0.999848,-1.000000,-0.999848,-0.999391,-0.998630,-0.997564,-0.996195,-0.994522,-0.992546,-0.990268,-0.987688,-0.984808,-0.981627,-0.978148,-0.974370,-0.970296,-0.965926,-0.961262,-0.956305,-0.951057,-0.945519,-0.939693,-0.933580,-0.927184,-0.920505,-0.913546,-0.906308,-0.898794,-0.891007,-0.882948,-0.874620,-0.866025,-0.857167,-0.848048,-0.838671,-0.829038,-0.819152,-0.809017,-0.798636,-0.788011,-0.777146,-0.766045,-0.754710,-0.743145,-0.731354,-0.719340,-0.707107,-0.694658,-0.681998,-0.669131,-0.656059,-0.642788,-0.629321,-0.615662,-0.601815,-0.587785,-0.573577,-0.559193,-0.544639,-0.529919,-0.515038,-0.500000,-0.484810,-0.469472,-0.453991,-0.438371,-0.422618,-0.406737,-0.390731,-0.374607,-0.358368,-0.342020,-0.325568,-0.309017,-0.292372,-0.275638,-0.258819,-0.241922,-0.224951,-0.207912,-0.190809,-0.173648,-0.156435,-0.139173,-0.121870,-0.104529,-0.087156,-0.069757,-0.052336,-0.034900,-0.017453,};