Exception: std::bad_alloc at memory location ... with SparseMat

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int mat_size_o = 60 * 60 * 60;

int sz[] = { 10000, mat_size_o };

SparseMat mem1(2, sz, CV_8UC1);

int idx[2];

for (int i = 0; i < 60; ++i) {
    for (int j = 0; j < 60; ++j) {
        for (int k = 0; k < 60; ++k) {
            int IOut = 60 * 60 * i + 60 * j + k;
            Out = calc_sum(IOut);
            Outp.at<float>(i, j, k) = Out;
        }
    }
}
float calc_sum(int IOut) {
int Sum0 = 0;
float Sum = 0;
int IIn0;
int IIn;
uchar Char;
for (int i = 0; i < nrows_i; ++i) { 
    IIn0 = ncols_i * i;
    for (int j = 0; j < ncols_i; ++j) {
        IIn = IIn0 + j;
        idx[0] = IIn;
        idx[1] = IOut;
        Char = mem1.ref<uchar>(idx);

        Sum0 += Char;
    }
}
Sum = Sum0;
return Sum;
}

Generates exception at i=0, j=4, k=59; For another matrix at i=0, j=6, k=59 It happens inside calc_sum() at Char = mem1.ref<uchar>(idx); when i = 43, j = 3 (nrows_i = ncols_i = 100). Initially I mixed int with unsigned int sometimes, but correction doesn't help. Did anybody encounter such errors?