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copied!<p>I would implement this as a ragged array, with A[n][0] always returning the element on the diagonal. A[n][1] will return the item just to the right of the diagonal, A[n][2] will return the item to the left of the diagonal, and so. Then, you just need a function that maps matrix index [i,j] to ragged array index[r][s].</p> <p>This has the advantage of sparsity, and if your values stay close to the diagonal the arrays are not very long.</p> <hr> <p>Alternatively, you could have this definition:</p> <pre><code>struct Row { int InitialOffset; int NumElements; int[] Values; } </code></pre> <p>Then you would have a Row[]. Retrieving a value based on matrix index would look like this:</p> <pre><code>//matrix is merely an array of rows... int GetValue(*matrix this, int i, int j) { Row CurrentRow = (*this)[i]; if (CurrentRow.InitialOffset > j) return 0; else if (CurrentRow.InitialOffset + CurrentRow.NumElements < j) return 0; return CurrentRow.Values[j - CurrentRow.InitialOffset] } </code></pre> <p>My C syntax is a little hazy, but you should get the idea.</p> <hr> <p>Based on your demonstration, I would recommend this:</p> <pre><code>struct Matrix { int[,] Data int[] StartOffset; int[] NumberElements; } </code></pre> <p>Used as follows...</p> <pre><code>int GetValue(*Matrix this, int i, int j) { if (this.StartOffset[i] > j) return 0; else if (this.StartOffset[i] + this.NumberElements[i] < j) return 0; return this.Data[i, j-this.StartOffset[i]]; } </code></pre> <p>Your initialization procedure would look something like this</p> <pre><code>//Data is a struct that holds row index, col index, and value Matrix* InitMatrix (*Data values, int numVals) { //loop through values to find longest row and number of rows //create new matrix, malloc matrix for longrow * numRows //malloc numrows elements for StartOffset and NumItems //foreach row, find min() and max()-min() of col indexs and //store in StartOffset and NumItems } </code></pre> <p>You need to do some processing, but data compression isn't cheap.</p>

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