NF4 Level Lookup

Problem

Look up an NF4 (4-bit NormalFloat) quantization level. NF4 uses the 16 fixed levels from -1.0 to 1.0 indexed by code 0-15, with non-uniform spacing dense near zero. Return level[code] * scale + zero_point.

The signature is nf4_level_lookup(code, scale, zero_point=0.0).

Hint

NF4 levels are quantiles of a standard normal, not uniformly spaced.

Test cases

case 1

in: [7,1,0]

expected: 0

case 2

in: [15,1,0]

expected: 1

case 3

in: [0,2,0.5]

expected: -1.5

case 4

in: [8,1,0]

expected: 0.07958029955625534

case 5

in: [1,1,0]

expected: -0.6961928009986877

Starter codePython

def nf4_level_lookup(code, scale, zero_point=0.0):
    # Your code here
    pass

5 test cases · run your code against them in the editor