Energize the cores

1,024 cores sit cold and dark. Each one is a single GPU thread, waiting for an instruction. Wake them: every core grabs one reading from the input buffer and doubles its energy.

This is the map pattern, one thread per element, the most fundamental GPU operation. The same shape powers a per-pixel image filter.

↳ Recall: i is this core's own global index, its one slot in the buffer. briefing ↗

GRID → BLOCKS → THREADS

The grid is split into blocks; each block holds the same threads (here 4). block_idx says which block, thread_idx says which thread inside it (0..3). Global index i = block_dim × block_idx + thread_idx. Highlighted: block 1, thread 2 → 4×1 + 2 = 6.

YOUR TASK

1The thread index i is already computed for you.
2Inside the guard, write the doubled value to out[i].

💡 Each core touches exactly one element: out[i] = inp[i] * 2.0

core_01_map.mojo

PUZZLE 1 · MAP

Clear all 8 chapters to forge⚡ Cold Boot Core Shard