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/* $OpenBSD: paskha.c,v 1.7 2015/03/15 00:41:28 millert Exp $ */ |
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/* |
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* Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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#include <stdio.h> |
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#include "calendar.h" |
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/* return year day for Orthodox Easter using Gauss formula */ |
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/* (new style result); subtract 13 for old style */ |
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int |
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paskha(int R) /*year*/ |
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{ |
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int a, b, c, d, e; |
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static int x = 15; |
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static int y = 6; |
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int cumdays; |
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a = R % 19; |
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b = R % 4; |
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c = R % 7; |
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d = (19*a + x) % 30; |
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e = (2*b + 4*c + 6*d + y) % 7; |
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cumdays = 31 + 28; |
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if (isleap(R)) |
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cumdays++; |
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return ((cumdays + 22) + (d + e) + 13); |
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} |