`mul`¶

Elementwise product of two tensors with identical shapes.

Category: arithmetic · Identity: mul@1

Shape¶

a[B, ...], b[B, ...] -> out[B, ...]

Port	Direction	Pattern	dtype
`a`	input	`a[B, ...]`	compute
`b`	input	`b[B, ...]`	compute
`out`	output	`out[B, ...]`	compute

Arguments¶

This operator takes no scalar arguments.

Description¶

out = a * b (the Hadamard product) with no broadcasting; the two operands must agree on rank, every axis extent, and dtype, and the product is computed in the plan compute dtype. Both tensor inputs must be supplied explicitly. Use scale instead to multiply by a constant.

Examples¶

Example 1¶

A gate: a second branch scales the first elementwise.

h = linear(4)
g = linear(x, 4)
g = tanh(g)
mul(h, g)

Input ['B', 8] → output ['B', 4].

Network: [B, 8] -> [B, 4]  dtype=float32
index  name  operation  input shapes        output shapes
0      n0    linear     x=[B, 8]            out=[B, 4]
1      n1    linear     x=[B, 8]            out=[B, 4]
2      n2    tanh       x=[B, 4]            out=[B, 4]
3      n3    mul        a=[B, 4], b=[B, 4]  out=[B, 4]

Parameters: 72

Example 2¶

Sequences work too: the two halves of the feature axis are multiplied.

a, b = split(4, dim=2)
mul(a, b)

Input ['B', 6, 8] → output ['B', 6, 4].

Network: [B, 6, 8] -> [B, 6, 4]  dtype=float32
index  name  operation  input shapes              output shapes
0      n0    split      x=[B, 6, 8]               first=[B, 6, 4], rest=[B, 6, 4]
1      n1    mul        a=[B, 6, 4], b=[B, 6, 4]  out=[B, 6, 4]

Parameters: 0

Example 3¶

Images: the operand shapes must match exactly.

mask = x
conv(3, kernel_size=3, padding=1)
h = tanh()
mul(h, mask)

Input ['B', 3, 8, 8] → output ['B', 3, 8, 8].

Network: [B, 3, 8, 8] -> [B, 3, 8, 8]  dtype=float32
index  name  operation  input shapes                    output shapes
0      n0    conv       x=[B, 3, 8, 8]                  out=[B, 3, 8, 8]
1      n1    tanh       x=[B, 3, 8, 8]                  out=[B, 3, 8, 8]
2      n2    mul        a=[B, 3, 8, 8], b=[B, 3, 8, 8]  out=[B, 3, 8, 8]

Parameters: 84

mul¶