doc and test: minor modifications

src/model/linmodel.jl

@@ -136,7 +136,7 @@ LinModel with a sample time Ts = 0.1 s:
 
     It is assumed that ``\mathbf{D_u=0}`` (or `sys` is strictly proper) since otherwise the
     resulting discrete controller would be acausal in its implementation (≠ mathematical
-    causality). Indeed, at each sampling instant `k`, the predictive controller will:
+    causality). Indeed, at each sampling instant ``k``, the predictive controller will:
 
     1. sample an output ``\mathbf{y}(k)`` from the plant
     2. computes an action ``\mathbf{u}(k)`` and 

test/3_test_predictive_control.jl

@@ -1480,7 +1480,7 @@ end
     f = (x, u, _, p) -> p.A * x + p.Bu * u
     h = (x, _, p)    -> p.C * x
     nonlinmodel = NonLinModel(f, h, 100.0, 1, 1, 1, p=linmodel, solver=nothing)
-    Mwt, Nwt, Hp, Hc = [1], [0], 30, [1, 2, 3, 24]
+    Mwt, Nwt, Hp, Hc = [1], [0], 30, [2, 3, 4, 21]
     N = 25
     mpc1 = LinMPC(linmodel; Mwt, Nwt, Hp, Hc, transcription=SingleShooting())
     mpc2 = LinMPC(linmodel; Mwt, Nwt, Hp, Hc, transcription=MultipleShooting())