add missing code snippets for newer Matrix methods and PartialLU::solve()
diff --git a/doc/snippets/Matrix_setConstant_int.cpp b/doc/snippets/Matrix_setConstant_int.cpp
new file mode 100644
index 0000000..ff5a86c
--- /dev/null
+++ b/doc/snippets/Matrix_setConstant_int.cpp
@@ -0,0 +1,3 @@
+VectorXf v;
+v.setConstant(3, 5);
+cout << v << endl;
diff --git a/doc/snippets/Matrix_setConstant_int_int.cpp b/doc/snippets/Matrix_setConstant_int_int.cpp
new file mode 100644
index 0000000..32b950c
--- /dev/null
+++ b/doc/snippets/Matrix_setConstant_int_int.cpp
@@ -0,0 +1,3 @@
+MatrixXf m;
+m.setConstant(3, 3, 5);
+cout << m << endl;
diff --git a/doc/snippets/Matrix_setIdentity_int_int.cpp b/doc/snippets/Matrix_setIdentity_int_int.cpp
new file mode 100644
index 0000000..a659671
--- /dev/null
+++ b/doc/snippets/Matrix_setIdentity_int_int.cpp
@@ -0,0 +1,3 @@
+MatrixXf m;
+m.setIdentity(3, 3);
+cout << m << endl;
diff --git a/doc/snippets/Matrix_setOnes_int.cpp b/doc/snippets/Matrix_setOnes_int.cpp
new file mode 100644
index 0000000..752cb35
--- /dev/null
+++ b/doc/snippets/Matrix_setOnes_int.cpp
@@ -0,0 +1,3 @@
+VectorXf v;
+v.setOnes(3);
+cout << v << endl;
diff --git a/doc/snippets/Matrix_setOnes_int_int.cpp b/doc/snippets/Matrix_setOnes_int_int.cpp
new file mode 100644
index 0000000..1ffb66b
--- /dev/null
+++ b/doc/snippets/Matrix_setOnes_int_int.cpp
@@ -0,0 +1,3 @@
+MatrixXf m;
+m.setOnes(3, 3);
+cout << m << endl;
diff --git a/doc/snippets/Matrix_setRandom_int.cpp b/doc/snippets/Matrix_setRandom_int.cpp
new file mode 100644
index 0000000..e160dd7
--- /dev/null
+++ b/doc/snippets/Matrix_setRandom_int.cpp
@@ -0,0 +1,3 @@
+VectorXf v;
+v.setRandom(3);
+cout << v << endl;
diff --git a/doc/snippets/Matrix_setRandom_int_int.cpp b/doc/snippets/Matrix_setRandom_int_int.cpp
new file mode 100644
index 0000000..80cda11
--- /dev/null
+++ b/doc/snippets/Matrix_setRandom_int_int.cpp
@@ -0,0 +1,3 @@
+MatrixXf m;
+m.setRandom(3, 3);
+cout << m << endl;
diff --git a/doc/snippets/Matrix_setZero_int.cpp b/doc/snippets/Matrix_setZero_int.cpp
new file mode 100644
index 0000000..0fb16c1
--- /dev/null
+++ b/doc/snippets/Matrix_setZero_int.cpp
@@ -0,0 +1,3 @@
+VectorXf v;
+v.setZero(3);
+cout << v << endl;
diff --git a/doc/snippets/Matrix_setZero_int_int.cpp b/doc/snippets/Matrix_setZero_int_int.cpp
new file mode 100644
index 0000000..ad883b9
--- /dev/null
+++ b/doc/snippets/Matrix_setZero_int_int.cpp
@@ -0,0 +1,3 @@
+MatrixXf m;
+m.setZero(3, 3);
+cout << m << endl;
diff --git a/doc/snippets/PartialLU_solve.cpp b/doc/snippets/PartialLU_solve.cpp
new file mode 100644
index 0000000..1244143
--- /dev/null
+++ b/doc/snippets/PartialLU_solve.cpp
@@ -0,0 +1,8 @@
+MatrixXd A = MatrixXd::Random(3,3);
+MatrixXd B = MatrixXd::Random(3,2);
+cout << "Here is the invertible matrix A:" << endl << A << endl;
+cout << "Here is the matrix B:" << endl << B << endl;
+MatrixXd X;
+if(A.lu().solve(B, &X))
+cout << "Here is the (unique) solution X to the equation AX=B:" << endl << X << endl;
+cout << "Relative error: " << (A*X-B).norm() / B.norm() << endl;