iGenfuner

Imaginer-Generate-function-er =>(iGenfuner) : Function generator and parser

• From this class name,you can know this a utils for Imaginer,It's use to parser(use RPN) a input string, maybe a math function or a math expression;
• From the parser result,must Generate a operate stream (op-stream), to save/record the function or expression Each step of the process;
• Then while you want to get a Special value(eg:1,2,3...),Will use the recorded op-stream, step-by-step calculation until the final results

Example

1. expression: -1.2*3-3+3+sin(-x+4*3-3+(1+5))*cos(x+7)*6+(-5+1)

   • change to RPN : 1.2 _ 3 * 3 - 3 + ? x _ 4 3 * + 3 - 1 5 + + $ ? x 7 + $ * 6 * + 5 _ 1 + +
   • ===============> calculate: 6 result: -5.35615
   • ===============> calculate: 5 result: -10.3544

2. expression: sin(-x+cos(cos(3+x)+6))+1+cos(-x)+3

   • change to RPN : ? x _ ? ? 3 x + $ 6 + $ + $ 1 + ? x _ $ + 3 +
   • ===============> calculate: 6 result: 5.56602
   • ===============> calculate: 5 result: 5.09643

3. expression: sin(x+cos(x))/3+9

   • change to RPN : ? x ? x $ + $ 3 / 9 +
   • ===============> calculate: 6 result: 9.20882
   • ===============> calculate: 5 result: 8.7196

NOTE

At The Example:

RPN expression have this letter:

• ? : function's index,because the index is < 0,so std::cout will show ?
• _ : minus; minus sign; negative indication; negative sign;
• $ : The end flag of the math function's arguments;

Function

• provide those function, but you can bind you function with user1 and user2

iGenFuner::sysFun iGenFuner::_sysfun[] =
{
    /*cmath provide such math funtion:*/
    self,   /*self(x)=x*/zero,    /*zero(x)=0*/  one,     /*one(x)=1*/  factorial,/*阶乘*/
    acos,   /*反余弦*/    asin,   /*反正弦*/      atan,   /*反正切*/      ceil,   /*上取整*/
    cos,    /*余弦*/      cosh,   /*双曲余弦*/    exp,    /*指数值*/      fabs,   /*绝对值*/
    floor,  /*下取整*/    log,    /*对数*/        log10,  /*对数*/        sin,    /*正弦*/
    sqrt,   /*开方*/      tan,    /*正切*/        user1,  /*自定义函数1*/  user2   /*自定义函数2*/
};

std::string       iGenFuner::_sysfunS[] =
{
    "self",   /*self(x)=x*/ "zero",   /*zero(x)=0*/ "one",     /*one(x)=1*/  "factorial",/*阶乘*/
    "acos",   /*反余弦*/    "asin",   /*反正弦*/      "atan",   /*反正切*/      "ceil",   /*上取整*/
    "cos",    /*余弦*/      "cosh",   /*双曲余弦*/    "exp",    /*指数值*/      "fabs",   /*绝对值*/
    "floor",  /*下取整*/    "log",    /*对数*/        "log10",  /*对数*/        "sin",    /*正弦*/
    "sqrt",   /*开方*/      "tan",    /*正切*/        "user1",  /*自定义函数1*/  "user2"   /*自定义函数2*/
};

• bind function usage:

  • user1 & user2 is Custom math function,you can set you want math function,but you need bind at first Here is a example or usge;

  • NOTE: Here is just provide two entry:user1 & user2 ,you just bind with bind1 to user1; bind2 to user2. You can get user1 with User1,user2 with User2.

    • bind1 ： bind a function with user1;
    • bind2 ： bind a function with user2;
    • User1 ： get the user1 function you set;
    • User2 ： get the user2 function you set;

• Add js version Genfuner for wx-Canvas,Just want to use at WeChat-small-program

  • NOTE:The binduser function is missing

//A example you Custom math function's implement
double you(double x)
{
    return cos(x)+5;
}
//======at main========
iGenFuner gf;
gf.bind1(you);                //bind you function with function point
gf.setExp("sin(x)+user1(x)"); //set expression for parser and generator
std::cout << "cos(4)+5: " << gf.User1()(4) << std::endl;
std::cout << "sin(4)+user1(4) = sin(4)+cos(4)+5: " << gf(4) << std::endl;

• Here bind example with calculate cos(4)+5, and retuen result;

Function index

• The function's index is get from here code :

#define FUNNUM  20   //this is number of sysFun,now(2017-1-8 10:00),It's 20
#define FUN_INDEX_RANGE (-128+FUNNUM)

char   iRpn::getFun(std::string funname)
{
    char index = -1;
    while(++index < FUNNUM && funname != _sysfunS[index]);
    return (index - 128);
}