Table of Contents

Mojo function

sum

fn def sum[dtype: DType, input_fn: def[width: Int, rank: Int](IndexList[rank]) capturing thin -> SIMD[dtype, width], output_fn: def[width: SIMDLength, rank: Int](IndexList[rank], SIMD[dtype, width]) capturing thin -> None, /, target: StringSpan[ImmStaticOrigin] = StringSpan("cpu"), *, reduce_dim: Int](input_shape: Coord)

Computes the sum across the input and output shape.

This performs the sum computation on the domain specified by input_shape, loading the inputs using the input_fn. The results are stored using the output_fn.

Parameters:

  • dtype (DType): The dtype of the input and output.
  • input_fn (def[width: Int, rank: Int](IndexList[rank]) capturing thin -> SIMD[dtype, width]): The function to load the input.
  • output_fn (def[width: SIMDLength, rank: Int](IndexList[rank], SIMD[dtype, width]) capturing thin -> None): The function to store the output.
  • target (StringSpan[ImmStaticOrigin]): The target to run on.
  • reduce_dim (Int): The axis to perform the sum on.

Args:

  • input_shape (Coord): The input shape.

Raises:

If the operation fails.

fn def sum[dtype: DType](src: Span[Scalar[dtype]]) -> Scalar[dtype]

Computes the sum of buffer elements.

Parameters:

  • dtype (DType): The dtype of the input.

Args:

  • src (Span[Scalar[dtype]]): The buffer.

Returns:

Scalar[dtype]: The sum of the buffer elements.

Raises:

If the operation fails.

fn def sum[dtype: DType, input_fn_1d: def[dtype_: DType, width: Int](idx: Int) capturing thin -> SIMD[dtype_, width]](length: Int) -> Scalar[dtype]

Computes the sum of a 1D array using a provided input function.

This function performs a reduction (sum) over a 1-dimensional array of the specified length and data type. The input values are provided by the input_fn_1d function, which takes an index and returns a SIMD vector of the specified width and data type. The reduction is performed using a single thread for deterministic results.

Parameters:

  • dtype (DType): The data type of the elements to sum.
  • input_fn_1d (def[dtype_: DType, width: Int](idx: Int) capturing thin -> SIMD[dtype_, width]): A function that takes a data type, SIMD width, and index, and returns a SIMD vector of input values.

Args:

  • length (Int): The number of elements in the 1D array.

Returns:

Scalar[dtype]: The sum of all elements as a scalar of the specified data type.

Raises:

Any exception raised by the input function or reduction process.

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