added type assertion in determinant methods
added type assertion in determinant methods

funkey/vigra,funkey/vigra,funkey/vigra,funkey/vigra,funkey/vigra,dstoe/vigra,dstoe/vigra,dstoe/vigra,dstoe/vigra,dstoe/vigra,dstoe/vigra,dstoe/vigra,funkey/vigra,funkey/vigra