diff --git a/HW6Problem2.m b/HW6Problem2.m
index a56c1b2..85c37d8 100644
--- a/HW6Problem2.m
+++ b/HW6Problem2.m
@@ -7,7 +7,6 @@ a = figure(1);
 set(0, 'defaultAxesFontsize', 16)
 set(0, 'defaultTextFontsize', 16)
 set(0, 'defaultLineLineWidth', 2)
-hold on
 t = [0:dt:3]';
 y_n = zeros(size(t));
 y_n(1) = 1; %initial condition
@@ -18,7 +17,7 @@ end
 plot(t, y_analytical(t), 'k-', t, y_n, 'o-');
 title('Analytical vs. Euler')
 legend('Analytical', 'Euler', 'Location', 'Northeast')
-saveas(a, 'euler.png');
+saveas(a, 'euler2.png');
 
 %Part c.
 b = figure(2);
@@ -26,4 +25,4 @@ y_heun = heun_sol_order1(@(t,y) ode2(t,y), dt, 1, [0 3]);
 plot(t, y_analytical(t), 'k-', t, y_heun, 'o-');
 title('Analytical vs. Heun')
 legend('Analytical', 'Heun', 'Location', 'Northeast')
-saveas(b, 'heun.png');
+saveas(b, 'heun2.png');
diff --git a/HW6Problem2.m~ b/HW6Problem2.m~
deleted file mode 100644
index 6f374b4..0000000
--- a/HW6Problem2.m~
+++ /dev/null
@@ -1,27 +0,0 @@
-%Part a.
-y_analytical = @(t) exp(-t);
-
-%Part b.
-dt = 0.01; %step size
-a = figure(1);
-set(0, 'defaultAxesFontsize', 16)
-set(0, 'defaultTextFontsize', 16)
-set(0, 'defaultLineLineWidth', 2)
-hold on
-t = [0:dt:3]';
-y_n = zeros(size(t));
-y_n(1) = 1; %initial condition
-for i = 2:length(t)
-	dy = ode2(t, y_n(i-1));
-    y_n(i) = y_n(i-1) + dt*dy;
-end
-plot(t, y_analytical(t), 'k-', t, y_n, 'o-');
-title('Analytical vs. Euler')
-legend('Analytical', 'Euler', 'Location', 'Northeast')
-saveas(a, 'euler.png');
-
-%Part c.
-b = figure(2)
-y_heun = heun_sol_order1(@(t,y) ode2(t,y), 1, 1, [0 3]);
-plot([0:1:3], y_heun);
-plot(t, y_analytical(t), 'k-', t, y_heun, 'o-');
diff --git a/HW6Problem3.m b/HW6Problem3.m
index ecd77ce..8ef85a8 100644
--- a/HW6Problem3.m
+++ b/HW6Problem3.m
@@ -1,23 +1,30 @@
-%Part b.
-dy = ode3(0, [1;0]);
-dt = [0.1 0.01 0.001];
-figure()
-hold on
-for k = 1:length(dt)
-    t = [0:dt(k):3]';
-    y_n = zeros(length(t), 2);
-    y_n(1, :) = [1 0]; %initial condition
-    for i = 2:length(t)
-        dy = ode3(t, y_n(i-1, :));
-        y_n(i, :) = y_n(i-1, :) + dt(k)*dy;
-    end
+%Part a.
+y_analytical = @(t) cos(3*t); 
 
-    plot(t, cos(3*t), 'k-', t, y_n(:,1), 'o-');
+%Part b.
+dt = 0.001; %step size
+a = figure(1);
+set(0, 'defaultAxesFontsize', 16)
+set(0, 'defaultTextFontsize', 16)
+set(0, 'defaultLineLineWidth', 2)
+t = [0:dt:3]';
+y_n = zeros(length(t), 2);
+y_n(1, :) = [1 0]; %initial condition
+for i = 2:length(t)
+    dy = ode3(t, y_n(i-1, :));
+	y_n(i, :) = y_n(i-1, :) + dt(k)*dy;
 end
+plot(t, y_analytical(t), 'k-', t, y_n(:,1), 'o-');
+title('Analytical vs. Euler')
+legend('Analytical', 'Euler', 'Location', 'Northeast')
+saveas(a, 'euler3.png');
 
 %Part c.
-figure()
+b = figure(2);
 dt = 0.001;
 t = [0:dt:3];
 y_heun = heun_sol_order2(@(t,y) ode3(t,y), dt, [1 0], [0 3]);
-plot(t, cos(3*t), 'k-', t, y_heun(:,1), 'o-');
\ No newline at end of file
+plot(t, y_analytical(t), 'k-', t, y_heun(:,1), 'o-');
+title('Analytical vs. Heun')
+legend('Analytical', 'Heun', 'Location', 'Northeast')
+saveas(b, 'heun3.png');
\ No newline at end of file
diff --git a/HW6Problem3.m~ b/HW6Problem3.m~
new file mode 100644
index 0000000..8fdfbc5
--- /dev/null
+++ b/HW6Problem3.m~
@@ -0,0 +1,26 @@
+%Part a.
+y_analytical = @(t) cos(3*t); 
+
+%Part b.
+dt = 0.01; %step size
+a = figure(1);
+set(0, 'defaultAxesFontsize', 16)
+set(0, 'defaultTextFontsize', 16)
+set(0, 'defaultLineLineWidth', 2)
+t = [0:dt:3]';
+y_n = zeros(length(t), 2);
+y_n(1, :) = [1 0]; %initial condition
+for i = 2:length(t)
+    dy = ode3(t, y_n(i-1, :));
+	y_n(i, :) = y_n(i-1, :) + dt(k)*dy;
+end
+
+    plot(t, cos(3*t), 'k-', t, y_n(:,1), 'o-');
+end
+
+%Part c.
+figure()
+dt = 0.001;
+t = [0:dt:3];
+y_heun = heun_sol_order2(@(t,y) ode3(t,y), dt, [1 0], [0 3]);
+plot(t, cos(3*t), 'k-', t, y_heun(:,1), 'o-');
\ No newline at end of file
diff --git a/README.md b/README.md
index 2a77514..4dc6d88 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,6 @@ a = figure(1);
 set(0, 'defaultAxesFontsize', 16)
 set(0, 'defaultTextFontsize', 16)
 set(0, 'defaultLineLineWidth', 2)
-hold on
 t = [0:dt:3]';
 y_n = zeros(size(t));
 y_n(1) = 1; %initial condition
@@ -35,5 +34,52 @@ legend('Analytical', 'Heun', 'Location', 'Northeast')
 saveas(b, 'heun.png');
 ```
 
-### Part a.
-![Analytical vs. Euler](./euler.png)
\ No newline at end of file
+### Part b.
+![Analytical vs. Euler](./euler2.png)
+
+### Part c.
+![Analytical vs. Heun](./heun2.png)
+
+## Problem 3
+
+### Script:
+```matlab
+%Part a.
+y_analytical = @(t) cos(3*t); 
+
+%Part b.
+dt = 0.001; %step size
+a = figure(1);
+set(0, 'defaultAxesFontsize', 16)
+set(0, 'defaultTextFontsize', 16)
+set(0, 'defaultLineLineWidth', 2)
+t = [0:dt:3]';
+y_n = zeros(length(t), 2);
+y_n(1, :) = [1 0]; %initial condition
+for i = 2:length(t)
+    dy = ode3(t, y_n(i-1, :));
+	y_n(i, :) = y_n(i-1, :) + dt(k)*dy;
+end
+plot(t, y_analytical(t), 'k-', t, y_n(:,1), 'o-');
+title('Analytical vs. Euler')
+legend('Analytical', 'Euler', 'Location', 'Northeast')
+saveas(a, 'euler3.png');
+
+%Part c.
+b = figure(2);
+dt = 0.001;
+t = [0:dt:3];
+y_heun = heun_sol_order2(@(t,y) ode3(t,y), dt, [1 0], [0 3]);
+plot(t, y_analytical(t), 'k-', t, y_heun(:,1), 'o-');
+title('Analytical vs. Heun')
+legend('Analytical', 'Heun', 'Location', 'Northeast')
+saveas(b, 'heun3.png');
+```
+
+### Part b.
+![Analytical vs. Euler](./euler3.png)
+
+### Part c.
+![Analytical vs. Heun](./heun3.png)
+
+## Problem 4
\ No newline at end of file
diff --git a/euler.png b/euler.png
deleted file mode 100644
index d929569..0000000
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diff --git a/euler3.png b/euler3.png
new file mode 100644
index 0000000..43dd612
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diff --git a/heun.png b/heun.png
deleted file mode 100644
index cdfc2f6..0000000
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diff --git a/heun3.png b/heun3.png
new file mode 100644
index 0000000..f20321d
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