from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A function of two variables that is equal to zero when the variables have different values and equal to one when the variables have the same value.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a function of two variables i and j that equals 1 when i=j and equals 0 otherwise
After Leopold Kronecker (1823-1891), German mathematician.(American Heritage® Dictionary of the English Language, Fourth Edition)
We just have to let the indices of the Kronecker delta run from 1 to 3.