confused by ggml_new_tensor_2d example

[sekirocc]

hi, I'm quite new to the ggml library and try to learn it. While reading the document, i came across the following example, and confused by the dimensions.

//   {
//       struct ggml_tensor * a = ggml_new_tensor_2d(ctx, GGML_TYPE_F32, 2, 3);
//
//       // a[1, 2] = 1.0f;
//       *(float *) ((char *) a->data + 2*a->nb[1] + 1*a->nb[0]) = 1.0f;
//
//       // a[2, 0] = 2.0f;
//       *(float *) ((char *) a->data + 0*a->nb[1] + 2*a->nb[0]) = 2.0f;
//
//       ...
//   }

from my limited understanding, a is a two dimension tensor, first dimension is 2, second dimension is 3. like c array float a[3][2]

my question is the following assignment:

//       // a[2, 0] = 2.0f;
//       *(float *) ((char *) a->data + 0*a->nb[1] + 2*a->nb[0]) = 2.0f;

it access the first dimension index with 2, isn't that an index-out-of-bounds operation? like a[0][2].

thanks in advance!

[ggerganov]

Oh wow - you right. Sorry about the confusion. Your understanding is the correct one. I'll fix the help

Edit: here is the new version:

https://github.com/ggerganov/ggml/blob/1a5d5f331de1d3c7ace40d86fe2373021a42f9ce/include/ggml/ggml.h#L130-L146