Excel函数使用——求逆矩阵和矩阵的值（Minverse和MDeterm）
帮网友解决求逆矩阵的问题。本文的重点是动态数组的使用和SAFEARRAY转换成普通数组的方法（也就是SafeArrayGetElement函数的使用）。
//定义测试数组
int arg2[3][3] = {1, 2, 1,
3, 4, -1,
0, 2, 0};
//计算(这个方法没变）
VARIANT varArg1;
SAFEARRAY *psa;
SAFEARRAYBOUND rgsabound[2];
rgsabound[0].lLbound = 0;//该维的下界
rgsabound[0].cElements = 3;//该维的元素个数
rgsabound[1].lLbound = 0;
rgsabound[1].cElements = 3;
long lIndex[2];
psa = SafeArrayCreate(VT_I4, 2, rgsabound); //二维
for (long k = 0; k < (long)3; k++)
{
lIndex[0] = k;
for ( long num = 0; num < (long)3; num++ )
{
lIndex[1] = num;
SafeArrayPutElement (psa, lIndex, &arg2[k][num]); //
}
}
varArg1.vt = VT_ARRAY | VT_I4;//整型数组
varArg1.parray = psa;//存储数据
VARIANT varRet = oFun.MInverse( varArg1 );
//其实结果是正确的，只是开始没有找到提取逆矩阵的方法
//我通过计算矩阵值的函数来计算逆矩阵，结果与Excel中的吻合
double varVal = oFun.MDeterm( varRet );// 0.125,正确
//于是寻找提取逆矩阵的方法
//定义一个动态的二维数组
VARIANT** arg3;//此处必须用VARIANT类型
//根据逆矩阵的维数和大小分配空间
//先获取逆矩阵的信息
UINT uDim = SafeArrayGetDim( varRet.parray );
UINT uEleSize = SafeArrayGetElemsize( varRet.parray );
long nDim1UBound;
long nDim1LBound;
SafeArrayGetUBound( varRet.parray, 1, &nDim1UBound );
SafeArrayGetLBound( varRet.parray, 1, &nDim1LBound );
long nDim2UBound;
long nDim2LBound;
SafeArrayGetUBound( varRet.parray, 2, &nDim2UBound );
SafeArrayGetLBound( varRet.parray, 2, &nDim2LBound );
long nDim1Count = nDim1UBound - nDim1LBound + 1;
long nDim2Count = nDim2UBound - nDim2LBound + 1;
//分配空间
arg3 = new VARIANT *[nDim1UBound];
for ( int nn = 0; nn < nDim1UBound; nn++ )
{
arg3[nn] = new VARIANT[nDim2UBound];
}
//提取逆矩阵
int x = 0;
int y = 0;
for ( long nDim1 = nDim1LBound; nDim1 <= nDim1UBound; nDim1++ )
{
lIndex[0] = nDim1;
y = 0;
for ( long nDim2 = nDim2LBound; nDim2 <= nDim2UBound; nDim2++ )
{
lIndex[1] = nDim2;
SafeArrayGetElement (varRet.parray, lIndex, &arg3[x][y]); //
y++;
}
x++;
}
//输出测试结果
for (i = 0; i < nDim1UBound; i++ )
{
for ( int j = 0; j < nDim2UBound; j++ )
{
CString strMsg;
strMsg.Format( _T( "%f" ), arg3[i][j].dblVal );
AfxMessageBox( strMsg );
}
}
//释放内存
SafeArrayDestroyData( psa );
for ( nn = 0; nn < nDim1UBound; nn++ )
{
delete[] arg3[nn];
}
delete arg3;
//逆矩阵
0.250.25-0.75
000.5
0.75-0.25-0.25