forked from sheetjs/sheetjs
23 lines
585 B
JavaScript
23 lines
585 B
JavaScript
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function frac(x, D, mixed) {
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var sgn = x < 0 ? -1 : 1;
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var B = x * sgn;
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var P_2 = 0, P_1 = 1, P = 0;
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var Q_2 = 1, Q_1 = 0, Q = 0;
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var A = Math.floor(B);
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while(Q_1 < D) {
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A = Math.floor(B);
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P = A * P_1 + P_2;
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Q = A * Q_1 + Q_2;
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if((B - A) < 0.0000000005) break;
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B = 1 / (B - A);
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P_2 = P_1; P_1 = P;
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Q_2 = Q_1; Q_1 = Q;
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}
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if(Q > D) { Q = Q_1; P = P_1; }
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if(Q > D) { Q = Q_2; P = P_2; }
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if(!mixed) return [0, sgn * P, Q];
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if(Q===0) throw "Unexpected state: "+P+" "+P_1+" "+P_2+" "+Q+" "+Q_1+" "+Q_2;
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var q = Math.floor(sgn * P/Q);
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return [q, sgn*P - q*Q, Q];
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}
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