Matt Karma Points(MKP)

// Submitted by EthereumHistory (ethereumhistory.com)
contract owned {
    address public owner;

    function owned() {
        owner = msg.sender;
    }

    modifier onlyOwner {
        if (msg.sender != owner) throw;
        _
    }

    function transferOwnership(address newOwner) onlyOwner {
        owner = newOwner;
    }
}

contract tokenRecipient {
    function receiveApproval(address _from, uint256 _value, address _token);
}

contract MyToken is owned {
    function transfer(address _to, uint256 _value) {
        if (balanceOf[msg.sender] < _value) throw;
        if (balanceOf[_to] + _value < balanceOf[_to]) throw;
        if (frozenAccount[msg.sender]) throw;
        balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;
        Transfer(msg.sender, _to, _value);
    }

    string public name;

    string public symbol;

    uint8 public decimals;

    uint256 public sellPrice;

    uint256 public buyPrice;

    uint256 public totalSupply;

    mapping (address => uint256) public balanceOf;

    mapping (address => bool) public frozenAccount;

    mapping (address => mapping (address => uint256)) public allowance;

    mapping (address => mapping (address => uint256)) public spentAllowance;

    event Transfer(address indexed from, address indexed to, uint256 value);

    event FrozenFunds(address target, bool frozen);

    function MyToken(uint256 initialSupply, string tokenName, uint8 decimalUnits, string tokenSymbol, address centralMinter) {
        if (centralMinter != 0) owner = msg.sender;
        balanceOf[msg.sender] = initialSupply;
        name = tokenName;
        symbol = tokenSymbol;
        decimals = decimalUnits;
        totalSupply = initialSupply;
    }

    function approveAndCall(address _spender, uint256 _value) returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        tokenRecipient spender = tokenRecipient(_spender);
        spender.receiveApproval(msg.sender, _value, this);
        return true;
    }

    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        if (balanceOf[_from] < _value) throw;
        if (balanceOf[_to] + _value < balanceOf[_to]) throw;
        if (spentAllowance[_from][msg.sender] + _value > allowance[_from][msg.sender]) throw;
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        spentAllowance[_from][msg.sender] += _value;
        Transfer(_from, _to, _value);
        return true;
    }

    function () {
        throw;
    }

    function mintToken(address target, uint256 mintedAmount) onlyOwner {
        balanceOf[target] += mintedAmount;
        totalSupply += mintedAmount;
        Transfer(0, owner, mintedAmount);
        Transfer(owner, target, mintedAmount);
    }

    function freezeAccount(address target, bool freeze) onlyOwner {
        frozenAccount[target] = freeze;
        FrozenFunds(target, freeze);
    }

    function setPrices(uint256 newSellPrice, uint256 newBuyPrice) onlyOwner {
        sellPrice = newSellPrice;
        buyPrice = newBuyPrice;
    }

    function buy() {

        uint amount = msg.value / buyPrice;
        if (balanceOf[this] < amount) throw;
        balanceOf[msg.sender] += amount;
        balanceOf[this] -= amount;
        Transfer(this, msg.sender, amount);
    }

    function sell(uint256 amount) {
        if (balanceOf[msg.sender] < amount) throw;
        balanceOf[this] += amount;
        balanceOf[msg.sender] -= amount;
        msg.sender.send(amount * sellPrice);
        Transfer(msg.sender, this, amount);
    }
}