Solving the problem of javascript floating-point multiplication accuracy

Source: Internet
Author: User
Tags mul pow

Example 1

The basic idea is to turn the floating-point numbers into integers and divide them by the N-order of the equivalent 10. n is (the sum of the back lengths of two floating-point numbers).

  code is as follows copy code

function FXF (f1, F2) {
    f1 + = ';
    F2 + + ';
    var f1len = f1.spli T ('. ') [1].length,
        f2len = F2.split ('. ') [1].length;

    if (f1len) {
        f1 = F1.replace ('. ', ');
 & nbsp; }
    if (f2len) {
        F2 = F2.replace ('. ', ' );
   }
    Return F1 * F2/MATH.POW (F1len + F2len);
};

Example 2

The code is as follows Copy Code

multiplication function to get the exact result of the multiplication
Description: JavaScript multiplication results will be error, in two floating-point numbers are more obvious when multiplying. This function returns a more accurate result of the multiplication.
Call: Accmul (ARG1,ARG2)
return value: Arg1 times Arg2 's exact result
function Accmul (arg1, arg2) {
var m = 0, S1 = arg1.tostring (), S2 = arg2.tostring ();
try {m + = S1.split (".") [1].length} catch (e) {}
try {m + = S2.split (".") [1].length} catch (e) {}
Return number (S1.replace (".", "")) * Number (S2.replace (".", ""))/Math.pow (M)
}
Adding a Mul method to the number type is more convenient to call.
Number.prototype.mul = function (ARG) {
Return Accmul (ARG, this);
}

The precision problem of additional method

The code is as follows Copy Code

/Description: JavaScript addition results will be error, in addition to two floating-point numbers will be more obvious. This function returns a more precise addition result.
Call: Accadd (ARG1,ARG2)
return value: Arg1 plus arg2 's exact result
function Accadd (arg1, arg2) {
var r1, R2, M;
try {r1 = arg1.tostring (). Split (".") [1].length} catch (e) {r1 = 0}
try {r2 = arg2.tostring (). Split (".") [1].length} catch (e) {r2 = 0}
m = Math.pow (Math.max (R1, R2))
Return (ARG1 * m + arg2 * m)/M
}
Adding an Add method to the number type is more convenient to call.
Number.prototype.add = function (ARG) {
Return Accadd (ARG, this);
}

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