Add javadocs for Equation* classes

README.MD

@@ -32,4 +32,4 @@ In Russian - algorithm has name "Progonka" (метод прогонки).
 
 ## Usage notes
 
-Should be added later, at this moment - just read provided code
+Check classes javadocs

src/main/java/by/andd3dfx/math/pde/Equation.java

@@ -5,6 +5,9 @@
 import by.andd3dfx.math.Matrix;
 import by.andd3dfx.util.FileUtil;
 
+/**
+ * Base class. Used to avoid code duplication in child classes
+ */
 public abstract class Equation {
 
     protected int lbt;
@@ -14,6 +17,17 @@ public abstract class Equation {
     protected Area area;
     protected Matrix arr = new Matrix();
 
+    /**
+     * Create equation
+     *
+     * @param x1  left space coordinate
+     * @param x2  right space coordinate
+     * @param t2  right time coordinate
+     * @param lbt type of left border condition (1/2/3)
+     * @param rbt type of right border condition (1/2/3)
+     * @param lH  coefficient for 3rd border condition type of left border
+     * @param rH  coefficient for 3rd border condition type of right border
+     */
     public Equation(double x1, double x2, double t2, int lbt, int rbt, double lH, double rH) {
         assert (lbt >= 1 && lbt <= 3 && rbt >= 1 && rbt <= 3 && lH > 0 && rH > 0);
 
@@ -24,34 +38,79 @@ public Equation(double x1, double x2, double t2, int lbt, int rbt, double lH, do
         this.rh = rH;
     }
 
+    /**
+     * Create equation
+     *
+     * @param x1 left space coordinate
+     * @param x2 right space coordinate
+     * @param t2 right time coordinate
+     */
     public Equation(double x1, double x2, double t2) {
         this(x1, x2, t2, 1, 1, 1, 1);
     }
 
+    /**
+     * Initial condition U0(x)
+     *
+     * @param x coordinate
+     * @return U value in asked coordinate
+     */
     protected double gU0(double x) {
         return 0;
     }
 
+    /**
+     * Left border condition U_left(t) (for 1st border type)
+     *
+     * @param t time
+     * @return U value in asked time moment on left border
+     */
     protected double gLU(double t) {
         return 0;
     }
 
+    /**
+     * Right border condition U_right(t) (for 1st border type)
+     *
+     * @param t time
+     * @return U value in asked time moment on right border
+     */
     protected double gRU(double t) {
         return 0;
     }
 
+    /**
+     * Left border condition dU_dt_left(t) (for 2nd border type)
+     *
+     * @param t time
+     * @return dU_dt value in asked time moment on left border
+     */
     protected double gLdU_dx(double t) {
         return 0;
     }
 
+    /**
+     * Right border condition dU_dt_right(t) (for 2nd border type)
+     *
+     * @param t time
+     * @return dU_dt value in asked time moment on right border
+     */
     protected double gRdU_dx(double t) {
         return 0;
     }
 
+    /**
+     * Coefficient for 3rd border type of left border
+     * TODO: provide better description
+     */
     protected double gLTeta(double t) {
         return 0;
     }
 
+    /**
+     * Coefficient for 3rd border type of right border
+     * TODO: provide better description
+     */
     protected double gRTeta(double t) {
         return 0;
     }
@@ -72,6 +131,12 @@ protected double gF(double x, double t, double U) {
         return 0;
     }
 
+    /**
+     * Solve equation using provided space & time steps
+     *
+     * @param h   space step
+     * @param tau time step
+     */
     public void solve(double h, double tau) {
         assert (h > 0 && tau > 0);                      // установка шагов по пространственной и временной координатам
         area.x().reborn(area.x().left(), area.x().right(), h);
@@ -83,41 +148,65 @@ public void solve(double h, double tau) {
         }
     }
 
+    /**
+     * Save data U(x) for asked time moment
+     *
+     * @param fileName file name
+     * @param t        time
+     */
     public void sUt(String fileName, double t) {
-        sUt(fileName, new double[]{0, t}, 1);
+        sUt(fileName, new double[]{0, t});
     }
 
-    public void sUt(String fileName, double t[], int size) {
-        for (var i = 0; i < size; i++) {
+    /**
+     * Save data U(x) for asked time moments. So in result we get some set of slices for several time moments
+     *
+     * @param fileName file name
+     * @param t        times array
+     */
+    public void sUt(String fileName, double t[]) {
+        for (var t_i : t) {
             var tInterval = area.t();
-            assert (tInterval.left() <= t[i] && t[i] <= tInterval.right());
+            assert (tInterval.left() <= t_i && t_i <= tInterval.right());
         }
 
         var sb = new StringBuilder();
         for (var i = 0; i <= area.x().n(); i++) {
             sb.append(area.x().x(i));
-            for (int j = 0; j < size; j++) {
-                sb.append(" " + arr.data(area.t().i(t[j]), i));
+            for (var t_i : t) {
+                sb.append(" " + arr.data(area.t().i(t_i), i));
             }
             sb.append("\n");
         }
         FileUtil.serialize(fileName, sb);
     }
 
+    /**
+     * Save data U(t) for asked space coordinate x
+     *
+     * @param fileName file name
+     * @param x        space coordinate
+     */
     public void sUx(String fileName, double x) {
-        sUx(fileName, new double[]{0, x}, 1);
+        sUx(fileName, new double[]{0, x});
     }
 
-    public void sUx(String fileName, double x[], int size) {
-        for (int i = 0; i < size; i++) {
-            assert (area.x().left() <= x[i] && x[i] <= area.x().right());
+    /**
+     * Save data U(t) for asked space coordinates. So in result we get some set of slices for several space coordinates
+     *
+     * @param fileName file name
+     * @param x        coordinates array
+     */
+    public void sUx(String fileName, double x[]) {
+        for (var x_i : x) {
+            assert (area.x().left() <= x_i && x_i <= area.x().right());
         }
 
         var sb = new StringBuilder();
         for (int i = 0; i <= area.t().n(); i++) {
             sb.append(area.t().x(i));
-            for (int j = 0; j < size; j++) {
-                sb.append(" " + arr.data(i, area.x().i(x[j])));
+            for (var x_i : x) {
+                sb.append(" " + arr.data(i, area.x().i(x_i)));
             }
             sb.append("\n");
         }
@@ -162,6 +251,9 @@ protected Matrix gUx(double x) {
         return gUx(area.x().i(x));
     }
 
+    /**
+     * Метод прогонки
+     */
     protected void progonka(int N, double[] A, double[] B, double[] C, double[] F, double m1, double n1, double m2, double n2, double[] Y) {
         double[] Alpha = new double[N + 1];
         double[] Beta = new double[N + 1];

src/main/java/by/andd3dfx/math/pde/HyperbolicEquation.java

@@ -2,14 +2,38 @@
 
 public class HyperbolicEquation extends Equation {
 
+    /**
+     * Create hyperbolic equation
+     *
+     * @param x1 left space coordinate
+     * @param x2 right space coordinate
+     * @param t2 right time coordinate
+     * @param lbt type of left border condition (1/2/3)
+     * @param rbt type of right border condition (1/2/3)
+     * @param lH coefficient for 3rd border condition type of left border
+     * @param rH coefficient for 3rd border condition type of right border
+     */
     public HyperbolicEquation(double x1, double x2, double t2, int lbt, int rbt, double lH, double rH) {
         super(x1, x2, t2, lbt, rbt, lH, rH);
     }
 
+    /**
+     * Create hyperbolic equation
+     *
+     * @param x1 left space coordinate
+     * @param x2 right space coordinate
+     * @param t2 right time coordinate
+     */
     public HyperbolicEquation(double x1, double x2, double t2) {
         this(x1, x2, t2, 1, 1, 1, 1);
     }
 
+    /**
+     * Solve equation using provided space & time steps
+     *
+     * @param h   space step
+     * @param tau time step
+     */
     @Override
     public void solve(double h, double tau) {
         super.solve(h, tau);

src/main/java/by/andd3dfx/math/pde/ParabolicEquation.java

@@ -2,14 +2,38 @@
 
 public class ParabolicEquation extends Equation {
 
+    /**
+     * Create parabolic equation
+     *
+     * @param x1 left space coordinate
+     * @param x2 right space coordinate
+     * @param t2 right time coordinate
+     * @param lbt  type of left border condition (1/2/3)
+     * @param rbt  type of right border condition (1/2/3)
+     * @param lH coefficient for 3rd border condition type of left border
+     * @param rH coefficient for 3rd border condition type of right border
+     */
     public ParabolicEquation(double x1, double x2, double t2, int lbt, int rbt, double lH, double rH) {
         super(x1, x2, t2, lbt, rbt, lH, rH);
     }
 
+    /**
+     * Create parabolic equation
+     *
+     * @param x1 left space coordinate
+     * @param x2 right space coordinate
+     * @param t2 right time coordinate
+     */
     public ParabolicEquation(double x1, double x2, double t2) {
         super(x1, x2, t2);
     }
 
+    /**
+     * Solve equation using provided space & time steps
+     *
+     * @param h   space step
+     * @param tau time step
+     */
     @Override
     public void solve(double h, double tau) {
         super.solve(h, tau);