unary

Identity function · x

Even the identity function f(x) = x takes non-trivial nesting in pure EML: ln(exp(x)) = x.

depth 4
Domain: x ∈ ℝ⁺
Definition
x = eml(1, eml(eml(1, eml(x, 1)), 1))x \ = \ \texttt{eml(1, eml(eml(1, eml(x, 1)), 1))}

Formula

eml(1, eml(eml(1, eml(x, 1)), 1))
Evaluate
2.5at x = 2.5

Reference: 2.5 2.5

EML tree
1111x2.511eml12.1825eml0.218311eml1.2439eml2.5

Click a node to highlight it. Each node shows its computed value below the label.

Step-through evaluation
  1. 1.depth 1const 1
  2. 2.depth 3const 1
  3. 3.depth 4x = 2.5
  4. 4.depth 4const 1
  5. 5.depth 3exp(2.5) − ln(1) = 12.182494
  6. 6.depth 2exp(1) − ln(12.182494) = 0.218282
  7. 7.depth 2const 1
  8. 8.depth 1exp(0.218282) − ln(1) = 1.243938
  9. 9.depth 0exp(1) − ln(1.243938) = 2.5
Derivation
  1. 1.Substitute z = exp(x) = eml(x, 1) into the ln(z) tree.
  2. 2.ln(exp(x)) = x by the fundamental log–exp identity.
  3. 3.Result: a depth-4 tree whose value equals x for any x.