Arrayfire稀疏矩阵定义问题求助：简单操作调试遇阻

Hey there! Let's figure out why you're stuck building that sparse matrix in Arrayfire. First, let's confirm the target dense matrix you want to create:

3  3  4
3 10  0
4  0  3

Your row, column, and values arrays actually look spot-on—they correctly map all the non-zero elements in your target matrix. The issue is almost certainly in how you're calling Arrayfire's sparse function (since your code cuts off at array rr = spar...).

Common Pitfalls to Fix #

Arrayfire's sparse constructor requires a few key parameters that might be missing from your code:

• Explicit matrix dimensions: You need to tell Arrayfire your matrix is 3 rows × 3 columns.
• Number of non-zero elements (nnz): You have 7 non-zero values, so this needs to be specified.
• Correct parameter order: The function expects values first, then row indices, column indices, dimensions, nnz, and optionally the storage format.

Working Code Example #

Here's the full, corrected code that will build your desired sparse matrix (and convert it to dense to verify):

#include <arrayfire.h>
#include <iostream>

using namespace af;

int main() {
    // Your original index and value arrays (they're correct!)
    int row[] = {0,0,0,1,1,2,2};
    int col[] = {0,1,2,0,1,0,2};
    double values[] = {3,3,4,3,10,4,3};
    
    // Define matrix properties
    const int total_rows = 3;
    const int total_cols = 3;
    const int non_zero_count = 7;
    
    // Construct the sparse matrix (using CSR storage, which matches your row-ordered indices)
    array sparse_matrix = sparse(values, row, col, dim4(total_rows, total_cols), non_zero_count, AF_STORAGE_CSR);
    
    // Convert to dense matrix to check if it matches your target
    array dense_matrix = dense(sparse_matrix);
    dense_matrix.print("Resulting Dense Matrix");
    
    return 0;
}

Why This Works #

• Your row/col/values arrays are already 0-indexed (which Arrayfire expects), so no adjustments needed there.
• We're using CSR (Compressed Sparse Row) storage, which aligns perfectly with how you've ordered your indices (grouped by rows).
• All required parameters are explicitly passed, so Arrayfire doesn't have to guess the matrix size or number of non-zero elements.

If you run this code, the printed dense matrix should exactly match the one you're trying to create.

内容的提问来源于stack exchange，提问作者user3000187