33 lines
1.3 KiB
JavaScript
33 lines
1.3 KiB
JavaScript
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"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.promoteLogarithm = promoteLogarithm;
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/**
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* Build a bigint logarithm function from a number logarithm,
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* still returning a number. The idea is that 15 hexadecimal digits
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* (60 bits) saturates the mantissa of the log, and each additional hex
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* digit effectively just adds the log of 16 to the resulting value. So
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* convert the most significant 15 hex digits to a number and take its
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* log, and then add the log of 16 for each additional hex digit that
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* was in the bigint.
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* For negative numbers (complex logarithms), following the bignum
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* implementation, it just downgrades to number and uses the complex result.
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* @param {number} log16 the log of 16
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* @param {(number) -> number} numberLog the logarithm function for numbers
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* @param {ConfigurationObject} config the mathjs configuration
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* @param {(number) -> Complex} cplx the associated Complex log
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* @returns {(bigint) -> number} the corresponding logarithm for bigints
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*/
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function promoteLogarithm(log16, numberLog, config, cplx) {
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return function (b) {
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if (b > 0 || config.predictable) {
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if (b <= 0) return NaN;
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const s = b.toString(16);
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const s15 = s.substring(0, 15);
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return log16 * (s.length - s15.length) + numberLog(Number('0x' + s15));
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}
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return cplx(b.toNumber());
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};
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}
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