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Add params to div, pow, and sqrt #200

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Add params to div, pow, and sqrt #200

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8869408
Add params to div, pow, and sqrt
martinglova Feb 1, 2023
af81a49
Update big.js
martinglova Feb 1, 2023
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40 changes: 20 additions & 20 deletions big.js
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Original file line number Diff line number Diff line change
Expand Up @@ -338,15 +338,17 @@

/*
* Return a new Big whose value is the value of this Big divided by the value of Big y, rounded,
* if necessary, to a maximum of Big.DP decimal places using rounding mode Big.RM.
* if necessary, to a maximum of params?.dp, or Big.DP (if params?.dp is not specified) decimal
* places using rounding mode params?.rm, or Big.RM (if params?.rm is not specified)
*/
P.div = function (y) {
P.div = function (y, params) {
var x = this,
Big = x.constructor,
a = x.c, // dividend
b = (y = new Big(y)).c, // divisor
k = x.s == y.s ? 1 : -1,
dp = Big.DP;
dp = params?.dp ?? Big.DP,
rm = params?.rm ?? Big.RM;

if (dp !== ~~dp || dp < 0 || dp > MAX_DP) {
throw Error(INVALID_DP);
Expand Down Expand Up @@ -441,7 +443,7 @@
}

// Round?
if (qi > p) round(q, p, Big.RM, r[0] !== UNDEFINED);
if (qi > p) round(q, p, rm, r[0] !== UNDEFINED);

return q;
};
Expand Down Expand Up @@ -621,12 +623,7 @@

if (ygtx) return new Big(x);

a = Big.DP;
b = Big.RM;
Big.DP = Big.RM = 0;
x = x.div(y);
Big.DP = a;
Big.RM = b;
x = x.div(y, { dp: 0, rm: 0 });

return this.minus(x.times(y));
};
Expand Down Expand Up @@ -724,12 +721,12 @@

/*
* Return a Big whose value is the value of this Big raised to the power n.
* If n is negative, round to a maximum of Big.DP decimal places using rounding
* mode Big.RM.
* If n is negative, round to a maximum of params?.dp, or Big.DP (if params?.dp is not specified)
* decimal places using rounding mode params?.rm, or Big.RM (if params?.rm is not specified).
*
* n {number} Integer, -MAX_POWER to MAX_POWER inclusive.
*/
P.pow = function (n) {
P.pow = function (n, params) {
var x = this,
one = new x.constructor('1'),
y = one,
Expand All @@ -748,7 +745,7 @@
x = x.times(x);
}

return isneg ? one.div(y) : y;
return isneg ? one.div(y, params) : params?.dp !== UNDEFINED || params?.rm !== UNDEFINED ? y.round(params?.dp, params?.rm) : y;
};


Expand Down Expand Up @@ -787,15 +784,18 @@

/*
* Return a new Big whose value is the square root of the value of this Big, rounded, if
* necessary, to a maximum of Big.DP decimal places using rounding mode Big.RM.
* necessary, to a maximum of params?.dp, or Big.DP (if params?.dp is not specified)
* decimal places using rounding mode params?.rm, or Big.RM (if params?.rm is not specified).
*/
P.sqrt = function () {
P.sqrt = function (params) {
var r, c, t,
x = this,
Big = x.constructor,
s = x.s,
e = x.e,
half = new Big('0.5');
half = new Big('0.5'),
dp = params?.dp ?? Big.DP,
rm = params?.rm ?? Big.RM;

// Zero?
if (!x.c[0]) return new Big(x);
Expand All @@ -820,15 +820,15 @@
r = new Big(s + '');
}

e = r.e + (Big.DP += 4);
e = r.e + (dp += 4);

// Newton-Raphson iteration.
do {
t = r;
r = half.times(t.plus(x.div(t)));
r = half.times(t.plus(x.div(t, { dp, rm })));
} while (t.c.slice(0, e).join('') !== r.c.slice(0, e).join(''));

return round(r, (Big.DP -= 4) + r.e + 1, Big.RM);
return round(r, (dp -= 4) + r.e + 1, rm);
};


Expand Down
20 changes: 18 additions & 2 deletions test/methods/div.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,8 @@ if (typeof test === 'undefined') require('../test');

test('div', function () {

function t(dividend, divisor, expected) {
test.areEqual(String(expected), String(new Big(dividend).div(divisor)));
function t(dividend, divisor, expected, params) {
test.areEqual(String(expected), String(new Big(dividend).div(divisor, params)));
}

Big.DP = 40;
Expand Down Expand Up @@ -9922,4 +9922,20 @@ test('div', function () {
Big.DP = 2;
t( 1, 4, '0.25');
t( 0.25, 1, '0.25');

// Using params.
t(0.034, 365, '0.0000931506', { dp: 10, rm: 0 });
t(0.034, 365, '0.0000931507', { dp: 10, rm: 1 });
t(0.034, 365, '0.0000931507', { dp: 10, rm: 2 });
t(0.034, 365, '0.0000931507', { dp: 10, rm: 3 });

t(0.034, 365, '0.00009315068493150684', { dp: 20, rm: 0 });
t(0.034, 365, '0.00009315068493150685', { dp: 20, rm: 1 });
t(0.034, 365, '0.00009315068493150685', { dp: 20, rm: 2 });
t(0.034, 365, '0.00009315068493150685', { dp: 20, rm: 3 });

t(0.034, 365, '0.000093150684931506849315068493', { dp: 30, rm: 0 });
t(0.034, 365, '0.000093150684931506849315068493', { dp: 30, rm: 1 });
t(0.034, 365, '0.000093150684931506849315068493', { dp: 30, rm: 2 });
t(0.034, 365, '0.000093150684931506849315068494', { dp: 30, rm: 3 });
});
26 changes: 24 additions & 2 deletions test/methods/pow.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,8 @@ if (typeof test === 'undefined') require('../test');
test('pow', function () {
var MAX_POWER = 1e6;

function t(expected, n, exp) {
test.areEqual(String(expected), String(new Big(n).pow(exp)))
function t(expected, n, exp, params) {
test.areEqual(String(expected), String(new Big(n).pow(exp, params)))
}

Big.DP = 20;
Expand Down Expand Up @@ -1129,6 +1129,28 @@ test('pow', function () {
t('-1e-99', '-62548432.8', -25);
t('1.22088300717794393478122381886210353872220530435821687360137756351400919646900089304893824e-10', '-90503', -2);

// Using params.
t('0.00000256', 0.2, 8, { dp: 8, rm: 0 });

t('0', 0.2, 8, { rm: 0 });
t('0.0000026', 0.2, 8, { dp: 7 });
t('0.00000256', 0.2, 8, {});

t('0.0000025', 0.2, 8, { dp: 7, rm: 0 });
t('0.0000026', 0.2, 8, { dp: 7, rm: 1 });
t('0.0000026', 0.2, 8, { dp: 7, rm: 2 });
t('0.0000026', 0.2, 8, { dp: 7, rm: 3 });

t('0.000002', 0.2, 8, { dp: 6, rm: 0 });
t('0.000003', 0.2, 8, { dp: 6, rm: 1 });
t('0.000003', 0.2, 8, { dp: 6, rm: 2 });
t('0.000003', 0.2, 8, { dp: 6, rm: 3 });

t('0.0069', 12, -2, { dp: 4, rm: 0 });
t('0.0069', 12, -2, { dp: 4, rm: 1 });
t('0.0069', 12, -2, { dp: 4, rm: 2 });
t('0.007', 12, -2, { dp: 4, rm: 3 });

/*
* Notes:
*
Expand Down
20 changes: 18 additions & 2 deletions test/methods/sqrt.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,8 @@ if (typeof test === 'undefined') require('../test');

test('sqrt', function () {

function t(root, value) {
test.areEqual(root, new Big(value).sqrt().toString())
function t(root, value, params) {
test.areEqual(root, new Big(value).sqrt(params).toString())
}

Big.DP = 20;
Expand Down Expand Up @@ -737,4 +737,20 @@ test('sqrt', function () {
Big.RM = 0;
t('9.9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999e+179', new Big('1e360').minus(1));
//t('9.999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999e+499', new Big('1e1000').minus(1));

// Using params.
t('3.4813790371', 12.12, { dp: 10, rm: 0 });
t('3.4813790371', 12.12, { dp: 10, rm: 1 });
t('3.4813790371', 12.12, { dp: 10, rm: 2 });
t('3.4813790372', 12.12, { dp: 10, rm: 3 });

t('3.48137903710584205614', 12.12, { dp: 20, rm: 0 });
t('3.48137903710584205614', 12.12, { dp: 20, rm: 1 });
t('3.48137903710584205614', 12.12, { dp: 20, rm: 2 });
t('3.48137903710584205615', 12.12, { dp: 20, rm: 3 });

t('3.481379037105842056144488334142', 12.12, { dp: 30, rm: 0 });
t('3.481379037105842056144488334143', 12.12, { dp: 30, rm: 1 });
t('3.481379037105842056144488334143', 12.12, { dp: 30, rm: 2 });
t('3.481379037105842056144488334143', 12.12, { dp: 30, rm: 3 });
});