2 am complex double conversion woes

This is a discussion on 2 am complex double conversion woes within the C++ Programming forums, part of the General Programming Boards category; Hey all, Its 2am im a little sleepy so I may be missing something elementary here; I have calculator from ...

  1. #1
    Registered User
    Join Date
    Oct 2004
    Posts
    19

    2 am complex double conversion woes

    Hey all,

    Its 2am im a little sleepy so I may be missing something elementary here;

    I have calculator from the relisoft site that ive been modifying.

    Code:
    main
    {input
    scanner
    parser}
    Been modifying it to implement complex numbers, using the <complex> standard with c++.

    So far so good; it can evaluate expressions like : (5 + j)/(5 + 16j) etc correctly.

    The program im modifying has a symbaltable where it has a list of functions, ive gone through every single declared double and checked to make sure its complex<double> now, but still when it tries to use any of the functions in the table:
    Code:
    symtab.cpp:57: error: invalid conversion from `double (*)(double) throw ()' to
       `std::complex<double> (*)(std::complex<double>)'
    Looked in stroustrups book, and the normal, cos, sin, exp functions are built in, cant understand why I cant change all the double types to complex and use the existing program structure? It works with operators... but functions... nope.

    Perhaps vague description, however whenever I post code, the nice people here go ahead and code the whole thing, which is more than what I need, and more of your time than I want to take.

    A suggestion as to what I may be overlooking would be fine.

    Edit: In case its too vague,
    symtab.cpp:
    Code:
    //------------------------------------
    //  symtab.cpp
    //  (c) Bartosz Milewski, 1994
    //------------------------------------
    
    #include "symtab.h"
    #include <cassert>
    #include <cstring>
    #include <iostream>
    #include <complex>
    using std::complex;
    using std::cout;
    using std::endl;
    
    complex<double> CoTan (complex<double> x) 
    {
        complex<double> y = tan (x);
        if (y.real() == 0)
        {
            cout << "cotan of " << x << " undefined\n";
            return HUGE_VAL;
        }
        return 1.0 / y;
    }           //do this for other funs
    
       complex<double> cos (complex<double> x)
    {
        complex<double> y = cos (x);
        if (y.real() == 0)
        {
            cout << "cotan of " << x << " undefined\n";
            return HUGE_VAL;
        }
        return 1.0 / y;
    }           //do this for other funs
    
    
    FunctionEntry funArr [maxIdFun] =
    { 
     //   log,  "log",
     //   log10,"log10",
     //     exp,  "exp",
     //   sqrt, "sqrt",
     //   sin,  "sin",
     //     cos,  "cos",
     //   tan,  "tan",
         CoTan,"cotan",
      //   sinh, "sinh",
     //   cosh, "cosh",
     //   tanh, "tanh",
     //   asin, "asin",
     //   acos, "acos",
     //   atan, "atan",
        0,    ""
    };
    
    FunctionTable::FunctionTable (SymbolTable & symTab, FunctionEntry funArr [])
        : _size(0)
    {
        for (int i = 0; i < maxIdFun; ++i)
        {
            int len =  strlen (funArr [i].strFun);
            if (len == 0)
                break;
            _pFun [i] = funArr [i].pFun;
            cout << funArr[i].strFun << endl;
            int j = symTab.ForceAdd (funArr[i].strFun, len);
            assert (i == j);
            ++_size;
        }
    }
    
    List::List ()
        : _pHead(0)
    {}
    
    List::~List ()
    {
        // free linked list
        while (_pHead != 0)
        {
            Link * pLink = _pHead;
            _pHead = _pHead->Next();
            delete pLink;
        }
    }
    
    void List::Add (int id)
    {
        // add in front of the list
        Link * pLink = new Link (_pHead, id);
        _pHead = pLink;
    }
    
    // Find the list in hash table that may contain
    // the id of the string we are looking for
    
    List const & HTable::Find (char const * str, int len) const
    {
        int i = hash (str, len);
        assert (i >= 0 && i < _size);
        return _aList [i];
    }
    
    void HTable::Add (char const * str, int len, int id)
    {
        int i = hash (str, len);
        assert (i >= 0 && i < _size);
        _aList [i].Add (id);
    }
    
    // Private hashing function
    
    int HTable::hash (char const * str, int len) const
    {
    
    
        // no empty strings, please
        assert (len != 0);
        // must be unsigned, hash should return positive number
        unsigned h = str [0];
        for (int i = 1; i < len; ++i)
            h = (h << 4) + str [i];
        return h % _size;  // small positive integer
    }
    
    SymbolTable::SymbolTable (int size)
        : _size (size), _curId (0), _curStrOff (0), _htab (size + 1)
    
    {
        _offStr = new int [size];
        _bufSize = size * 10;
        _strBuf = new char [_bufSize];
    }
    
    SymbolTable::~SymbolTable()
    {
        delete []_offStr;
        delete []_strBuf;
    }
    
    // Add string without looking for duplicates
    
    int SymbolTable::ForceAdd (char const * str, int len)
    {
        // is there enough space?
        if (_curId == _size
            || _curStrOff + len + 1 >= _bufSize)
        {
            return idNotFound;
        }
        // point to place where the string will be stored
        _offStr [_curId] = _curStrOff;
        // copy the string there
        strncpy (&_strBuf [_curStrOff], str, len);
        // calculate new offset
        _curStrOff += len;
        _strBuf [_curStrOff] = 0;  // null terminate
        ++_curStrOff;
        // add to hash table
        _htab.Add (str, len, _curId);
        ++_curId;
        return _curId - 1;
    }
    
    int SymbolTable::Find (char const * str, int len) const
    {
        // Get a short list from hash table
        List const & list = _htab.Find (str, len);
        // Iterate over this list
        for (Link const * pLink = list.GetHead ();
            pLink != 0;
            pLink = pLink->Next () )
        {
            int id = pLink->Id ();
            int offStr = _offStr [id];
            // char const * strStored = &_strBuf [ offStr ];
            char const * strStored = _strBuf + offStr;
            if (strcmp (str, strStored) == 0) // they're equal
            {
                return id;  // success!
            }
        }
        return idNotFound;
    }
    
    // map integer into string. Must be valid id
    
    char const * SymbolTable::GetString (int id) const
    {
        assert (id >= 0);
        assert (id < _curId);
        int offStr = _offStr [id];
        return &_strBuf [offStr];
        // return _strBuf + offStr;
    }
    symtab.h:
    Code:
    #if !defined SYMTAB_H
    #define SYMTAB_H
    //------------------------------------
    //  symtab.h
    //  (c) Bartosz Milewski, 1994
    //------------------------------------
    #include <cstring>
    #include <complex>
                              
    using std::complex;
    
    const int maxIdFun = 16;
    
    typedef complex<double> (*PFun) (complex<double> x);
    
    class FunctionEntry
    {
    public:
        PFun pFun;
        char* strFun;
    };
    
    extern FunctionEntry funArr [];
    
    class SymbolTable;
    
    class FunctionTable
    {
    public:
        FunctionTable (SymbolTable& symTab, FunctionEntry funArr []);
        int Size () const { return _size; }
        PFun GetFun (int id) { return _pFun [id]; }
    private:
        PFun  _pFun [maxIdFun];
        int   _size;
    };
    
    
    // stores integer id in a link
    class Link
    {
    public:
        Link (Link * pNext, int id)
        : _pNext (pNext), _id (id) {}
    
        Link *  Next () const { return _pNext; }
        int     Id () const { return _id; }
    private:
        Link *  _pNext;
        int     _id;
    };
    
    // Linked list of id's stored in links
    
    class List
    {
    public:
        List ();
        ~List ();
        void Add (int id);
        Link const * GetHead () const { return _pHead; }
    private:
        Link * _pHead;
    };
    
    // Hash table of strings
    
    class HTable
    {
    public:
        explicit HTable (int size): _size(size)
        {
            _aList = new List[size];
        }
    
        ~HTable ()
        {
            delete [] _aList;
        }
    
        List const & Find (char const * str, int len) const;
        List const & Find (char const * str) const
    	{
    		return Find (str, strlen (str));
    	}
        void Add (char const * str, int len, int id);
        void Add (char const * str, int id)
    	{
    		Add (str, strlen (str), id);
    	}
    private:
        int hash (char const * str, int len) const;
    
        List * _aList;
        int    _size;
    };
    
    const int idNotFound = -1;
    
    // String table maps strings to ints
    // and ints to strings
    
    class SymbolTable
    {
    public:
        explicit SymbolTable (int size);
        ~SymbolTable ();
        int ForceAdd (char const * str, int len);
        int Find (char const * str, int len) const;
        char const * GetString (int id) const;
    private:
        HTable  _htab;
        int *   _offStr; // offsets of strings in buffer
        int     _size;
        int     _curId;
        char *  _strBuf;
        int     _bufSize;
        int     _curStrOff;
    };
    #endif
    Last edited by Roule; 10-14-2004 at 10:15 AM.

  2. #2
    Registered User
    Join Date
    Sep 2004
    Posts
    719
    symtab.cpp:57: error: invalid conversion from `double (*)(double) throw ()' to
    `std::complex<double> (*)(std::complex<double>)'

    try return y / 1.0;
    or return y = y / 1.0;
    or return (complex<double>(1.0) / y); //this might be a syntax error

    i may be way off on this theory, but complex:perator/ function might return a double if the left hand operand is a double and the right hand operand is complex..and vice versa
    i seem to have GCC 3.3.4
    But how do i start it?
    I dont have a menu for it or anything.

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