1 | /* Compute projection of complex double value to Riemann sphere. |
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2 | Copyright (C) 1997, 1999 Free Software Foundation, Inc. |
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3 | This file is part of the GNU C Library. |
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4 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. |
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5 | |
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6 | The GNU C Library is free software; you can redistribute it and/or |
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7 | modify it under the terms of the GNU Lesser General Public |
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8 | License as published by the Free Software Foundation; either |
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9 | version 2.1 of the License, or (at your option) any later version. |
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10 | |
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11 | The GNU C Library is distributed in the hope that it will be useful, |
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12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 | Lesser General Public License for more details. |
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15 | |
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16 | You should have received a copy of the GNU Lesser General Public |
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17 | License along with the GNU C Library; if not, write to the Free |
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18 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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19 | 02111-1307 USA. */ |
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20 | |
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21 | #include <complex.h> |
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22 | #include <math.h> |
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23 | #include "math_private.h" |
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24 | |
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25 | __complex__ double |
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26 | __cproj (__complex__ double x) |
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27 | { |
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28 | __complex__ double res; |
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29 | |
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30 | if (isnan (__real__ x) && isnan (__imag__ x)) |
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31 | return x; |
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32 | else if (!isfinite (__real__ x) || !isfinite (__imag__ x)) |
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33 | { |
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34 | __real__ res = INFINITY; |
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35 | __imag__ res = __copysign (0.0, __imag__ x); |
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36 | } |
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37 | else |
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38 | { |
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39 | double den = __real__ x * __real__ x + __imag__ x * __imag__ x + 1.0; |
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40 | |
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41 | __real__ res = (2.0 * __real__ x) / den; |
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42 | __imag__ res = (2.0 * __imag__ x) / den; |
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43 | } |
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44 | |
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45 | return res; |
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46 | } |
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47 | weak_alias (__cproj, cproj) |
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48 | #ifdef NO_LONG_DOUBLE |
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49 | strong_alias (__cproj, __cprojl) |
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50 | weak_alias (__cproj, cprojl) |
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51 | #endif |
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