| 1 | // |
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| 2 | // C++ Interface: Locator |
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| 3 | // |
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| 4 | // Description: |
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| 5 | // |
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| 6 | // |
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| 7 | // Author: Takeshi Nakazato <takeshi.nakazato@nao.ac.jp>, (C) 2012 |
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| 8 | // |
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| 9 | // Copyright: See COPYING file that comes with this distribution |
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| 10 | // |
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| 11 | // |
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| 12 | #ifndef ASAP_LOCATOR_H |
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| 13 | #define ASAP_LOCATOR_H |
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| 14 | |
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| 15 | namespace asap { |
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| 16 | |
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| 17 | /** |
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| 18 | * Base class for locate operation |
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| 19 | * @author TakeshiNakazato |
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| 20 | */ |
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| 21 | class Locator { |
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| 22 | public: |
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| 23 | // Default constructor. |
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| 24 | Locator(); |
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| 25 | |
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| 26 | // Construct with data. |
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| 27 | // @param[in] v pointer to input data. |
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| 28 | // @param[in] n length of the data. |
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| 29 | // @param[in] copystorage whether allocate internal memory or not. |
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| 30 | // @see set() |
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| 31 | Locator(double *v, unsigned int n, bool copystorage=true); |
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| 32 | |
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| 33 | // Set data. The data must be sorted in either ascending or descending |
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| 34 | // order, and must not have any duplicate elements. |
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| 35 | // @param[in] v pointer to input data. |
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| 36 | // @param[in] n length of the data. |
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| 37 | // @param[in] copystorage whether allocate internal memory or not. |
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| 38 | // |
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| 39 | // Setting copystorage=false is bit faster since it directly points |
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| 40 | // to the input array instead to allocate memory and copy input array. |
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| 41 | // However, you have to be careful to set copystorage to false since |
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| 42 | // it will take a risk to allow to edit the data to be searched from |
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| 43 | // outside the class. |
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| 44 | void set(double *v, unsigned int n, bool copystorage=true); |
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| 45 | |
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| 46 | // Destructor. |
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| 47 | virtual ~Locator(); |
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| 48 | |
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| 49 | // Return right hand side index of location. |
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| 50 | // @param[in] x input value to be located. |
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| 51 | // @return location as an index j. |
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| 52 | // |
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| 53 | // Returned index j satisfies x_[j-1] < x <= x_[j] for ascending |
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| 54 | // case while x_[j-1] > x >= x_[j] for descending case. |
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| 55 | // Returned value 0 or x.nelements() indicates out of range. |
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| 56 | virtual unsigned int locate(double x) = 0; |
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| 57 | |
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| 58 | protected: |
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| 59 | // Bisection search. |
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| 60 | // @param[in] x input value to be located. |
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| 61 | // @param[in] left the leftmost index to search. |
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| 62 | // @param[in] right the rightmost index to search. |
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| 63 | unsigned int bisection(double x, unsigned int left, unsigned int right); |
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| 64 | |
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| 65 | // Hunt algorithm |
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| 66 | // @param[in] x input value to be located. |
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| 67 | // @param[in,out] left input: the starting point for hunt. |
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| 68 | // output: the left index of hunted region. |
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| 69 | // @param[out] right the right index of hunted region. |
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| 70 | void hunt(double x, unsigned int &left, unsigned int &right); |
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| 71 | |
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| 72 | // Pointer to the data. |
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| 73 | double *x_; |
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| 74 | |
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| 75 | // Length of the data. |
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| 76 | unsigned int n_; |
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| 77 | |
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| 78 | // Is data ascending or descending? |
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| 79 | bool ascending_; |
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| 80 | |
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| 81 | // Is internal storage allocated? |
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| 82 | bool copy_; |
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| 83 | }; |
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| 84 | |
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| 85 | } |
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| 86 | #endif |
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