Runge-Kutta method: Difference between revisions

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 =={{header|Excel}}==
-<syntaxhighlight lang="Excel">PRINT "RungaKutta4λ(D)"</syntaxhighlight>
+<syntaxhighlight lang="Excel">
-Worksheet formula to manage looping
+//Worksheet formula to manage looping
 =LET(
@@ Line 1,132: / Line 1,132: @@
 )
-Lambda function passed to RK4 to evaluate derivatives
+//Lambda function passed to RungaKutta4λ to evaluate derivatives
 Dλ(y,t)
 = LAMBDA(y,t, t * SQRT(y))
-Curried Lambda function with derivative function and y, t as parameters
+//Curried Lambda function with derivative function D and y, t as parameters
 RungaKutta4λ(Dλ)
 = LAMBDA(D,
-    LAMBDA(yᵣ, tᵣ,
+      LAMBDA(yᵣ, tᵣ,
-      LET(
+          LET(
-        δy₁, δt * D(yᵣ, tᵣ),
+              δy₁,   δt * D(yᵣ, tᵣ),
-        δy₂, δt * D(yᵣ + δy₁ / 2, tᵣ + δt / 2),
+              δy₂,   δt * D(yᵣ + δy₁ / 2, tᵣ + δt / 2),
-        δy₃, δt * D(yᵣ + δy₂ / 2, tᵣ + δt / 2),
+              δy₃,   δt * D(yᵣ + δy₂ / 2, tᵣ + δt / 2),
-        δy₄, δt * D(yᵣ + δy₃, tᵣ + δt),
+              δy₄,   δt * D(yᵣ + δy₃, tᵣ + δt),
-        yᵣ₊₁, yᵣ + (δy₁ + 2 * δy₂ + 2 * δy₃ + δy₄) / 6,
+              yᵣ₊₁,  yᵣ + (δy₁ + 2 * δy₂ + 2 * δy₃ + δy₄) / 6,
-        yᵣ₊₁
+              yᵣ₊₁
+          )
       )
-    )
   )
-Lambda function returning the exact solution
+//Lambda function returning the exact solution
 f(t)
-= LAMBDA(t, (1 / 16) * (t ^ 2 + 4) ^ 2 )
+= LAMBDA(t, (1/16) * (t^2 + 4)^2 )
+</syntaxhighlight>
-Results
 {{out}}
 <pre>