Injective is another term for onto.
f(x) is one-to-one provided u = v implies f(u) = f(v).
One-to-one means that different inputs give rise to the same output.
The set of outputs from a function is called the codomain.
If the image is all of the codamin, then the function is said to be one-to-one.
Surjective is another term for onto.
g(x) = 1 - |x| is surjective.
The projection T(x,y,z) = (x,y,0) from R3 to R2 is surjective.
The image of a linear transformation is a subspace of the codomain vector space.
The dimension of the image of a linear transformation T is called its codomain.
