Fixed a typo in a formula

doc/guide.tex

@@ -48,7 +48,7 @@ \chapter{Dense QP}
 \min_{v,s} & \quad \frac 1 2 \begin{bmatrix} v \\ 1 \end{bmatrix}^T \begin{bmatrix} H & g \\ g^T & 0 \end{bmatrix} \begin{bmatrix} v \\ 1 \end{bmatrix} + \frac 1 2 \begin{bmatrix} s^l \\ s^u \\ 1 \end{bmatrix}^T \begin{bmatrix} Z^l & 0 & z^l \\ 0 & Z^u & z^u \\ (z^l)^T & (z^u)^T & 0 \end{bmatrix} \begin{bmatrix} s^l \\ s^u \\ 1 \end{bmatrix} \\
 s.t. & \quad A v = b \\
 & \quad \begin{bmatrix} \underline v \\ \underline d \end{bmatrix} \leq \begin{bmatrix} J_{b,v} \\ C \end{bmatrix} v + \begin{bmatrix} J_{s,v} \\ J_{s,g} \end{bmatrix} s^l \\
-& \quad \begin{bmatrix} J_{b,v} \\ C_n \end{bmatrix} v - \begin{bmatrix} J_{s,v} \\ J_{s,g} \end{bmatrix} s^u \leq \begin{bmatrix} \overline v \\ \overline d \end{bmatrix} \\
+& \quad \begin{bmatrix} J_{b,v} \\ C_n \end{bmatrix} v - \begin{bmatrix} J_{s,v} \\ J_{s,g} \end{bmatrix} s^u \leq \begin{bmatrix} \overline v \\ \overline d \end{bmatrix}
 & \quad s^l\geq 0 \\
 & \quad s^u\geq 0
 \end{align*}
@@ -72,9 +72,15 @@ \chapter{OCP QP}
 \end{align*}
 where $u_n$ are the control inputs, $x_n$ are the states, $s^l_n$ ($s^u_n$) are the slack variables of the soft lower (upper) constraints.
 The matrices $J_{\dots,n}$ are made of rows from identity matrices.
+The matrices $J_{s,\dots}$ are made of rows from an identity matrix of size $n_s$ or of zeros.
+So there may well be no soft constraints ($n_s=0$), or only on some constraints (and then the other constraints have a row of zeros in $J_{s,\dots}$.)
+\texttt{idxs[j]=i} means that the element \texttt{[i,j]} of the stacked $J_{s,\dots}$ matrix is one.
+
 Note that all quantities can vary stage-wise.
 Furthermore, note that the constraint matrix with respect to $u$ and $x$ is the same for the upper and the lower constraints.
 
+
+
 \begin{verbatim}
 int d_memsize_ocp_qp(int N, int *nx, int *nu, int *nb, int *ng, int *ns);
 \end{verbatim}