Update FunctionPlotter to draw primes with Erathostenes

amaldoror · Jul 27, 2024 · b08e13d · b08e13d
1 parent de9a5be
commit b08e13d
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Showing 3 changed files with 18 additions and 1 deletion.
diff --git a/src/main/java/org/rancore/math/Erathostenes.java b/src/main/java/org/rancore/math/Erathostenes.java
@@ -33,7 +33,7 @@ public static boolean[] sieve(int n) {
     }
 
     public static void main(String[] args) {
-        int n = 300;
+        int n = 3000;
         boolean[] primes = sieve(n);
         System.out.print("Primzahlen bis " + n + ": ");
         for (int i = 2; i <= n; i++) {

diff --git a/src/main/java/org/rancore/math/plot/FunctionPlotter.java b/src/main/java/org/rancore/math/plot/FunctionPlotter.java
@@ -64,6 +64,7 @@ protected void paintComponent(Graphics g) {
         drawGrid(g2, width, height);
         drawAxis(g2, height, width);
         drawAxisScale(g2, width, height, scaleX, scaleY, rangeX, rangeY);
+        drawPrimes(g2, width, height);
         drawSquared(g2, width, height);
         drawFunction(g2, width, height);
     }

diff --git a/src/main/java/org/rancore/math/plot/GraphComponent.java b/src/main/java/org/rancore/math/plot/GraphComponent.java
@@ -1,5 +1,7 @@
 package org.rancore.math.plot;
 
+import org.rancore.math.Erathostenes;
+
 import java.awt.*;
 import java.util.ArrayList;
 import java.util.List;
@@ -83,6 +85,20 @@ static void drawFunction(Graphics2D g2, int width, int height) {
         }
     }
 
+    static void drawPrimes(Graphics2D g2, int width, int height) {
+        g2.setColor(Color.RED);
+        int n = 300;
+        boolean[] primes = Erathostenes.sieve(n);
+        for (int i = 2; i <= n; i++) {
+            if (primes[i]) {
+
+                g2.drawLine(i, height /2, width+i, height / 2*i);
+                g2.drawLine(i, height *2, width+i, height * 2*i);
+                System.out.print(i + " ");
+            }
+        }
+    }
+
     static void drawSquared(Graphics2D g2, int width, int height) {
         // Draw the function y = x^2
         g2.setColor(Color.RED);