#!/usr/local/src/cmd/calc/calc -q -f/* * powerterm - print the argument as a sum of powers of integers * * usage: *      powerterm [base_limit] value * *	base_limit	largest base we will consider (def: 10000) *      value		value to convert into sums of powers of integers * * Copyright (C) 2001  Landon Curt Noll * * Calc is open software; you can redistribute it and/or modify it under * the powerterm of the version 2.1 of the GNU Lesser General Public License * as published by the Free Software Foundation. * * Calc is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General * Public License for more details. * * A copy of version 2.1 of the GNU Lesser General Public License is * distributed with calc under the filename COPYING-LGPL.  You should have * received a copy with calc; if not, write to Free Software Foundation, Inc. * 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA. * * @(#) $Revision: 29.7 $ * @(#) $Id: powerterm.calc,v 29.7 2007/02/07 00:34:04 chongo Exp $ * @(#) $Source: /usr/local/src/cmd/calc/cscript/RCS/powerterm.calc,v $ * * Under source code control:   2001/04/24 23:49:11 * File existed as early as:    2001 * * chongo <was here> /\oo/\     http://www.isthe.com/chongo/ * Share and enjoy!  :-)        http://www.isthe.com/chongo/tech/comp/calc/ *//* * parse args */config("verbose_quit", 0),;base_lim = 10000;		/* default: highest base we will consider */if (argv() < 2 || argv() > 3) {    fprintf(files(2), "usage: %s [base_limit] value\n", argv(0));    exit;}if (argv() == 3) {    x = eval(argv(2));    base_lim = eval(argv(1));} else {    x = eval(argv(1));}if (! isint(x)) {    fprintf(files(2), "%s: value must be an integer\n");    exit;}if (! isint(base_lim)) {    fprintf(files(2), "%s: base limit must be an integer\n");    exit;}if (base_lim <= 1) {    fprintf(files(2), "%s: base limit is too small\n");    exit;}++base_lim;/* * setup loop variables */term = 0;			/* number of powerterm found *//* * log constants */if (base_lim <= 2^20+1) {		/* 2^20 requires ~96 Megs of memory */    mat lni[base_lim];			/* log of integers */    for (i=2; i < base_lim; ++i) {	lni[i] = ln(i);    }    have_lni = 1;			/* have lni[x] array */} else {    mat lni[1];				/* not used */    have_lni = 0;			/* base_lim too large for array */}/* * remove nestest powers */while (abs(x) >= base_lim) {    /*     * look for the nearest power     */    lnx = ln(abs(x));			/* log of the remaining co-factor */    closest = 0.5;    base = 1;    exponent = 0;    if (have_lni) {	/*	 * use pre-calculated log array when looking for the nearest power	 */	for (i = 2; i < base_lim; ++i) {	    /*	     * determine exponent closeness to an integer	     */	    ex = lnx / lni[i];	    power = int(ex + 0.5);	    diff = ex - power;	    /*	     * look for a closer power	     */	    if (abs(diff) < closest) {		closest = abs(diff);		base = i;		exponent = power;	    }	}    } else {	/*	 * re-calculate logs when looking for the nearest power	 */	for (i = 2; i < base_lim; ++i) {	    /*	     * determine exponent closeness to an integer	     */	    ex = lnx / ln(i);	    power = int(ex + 0.5);	    diff = ex - power;	    /*	     * look for a closer power	     */	    if (abs(diff) < closest) {		closest = abs(diff);		base = i;		exponent = power;	    }	}    }    /*     * output current term and then subtract it     */    if (x != 0) {	if (x < 0) {	    print "-",;	} else if (term > 0) {	    print "+",;	}	if (exponent > 1) {	    print base: "^": exponent,;	} else {	    print base,;	}    }    /*     * subtract (or add) this near power     */    if (x < 0) {	x = x + base^exponent;    } else {	x = x - base^exponent;    }    ++term;}/* * print the final term */if (x < 0) {    print "-", -x;} else if (x > 0) {    print "+", x;} else {    print "";}exit;