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+//Example 7.8
+//Stirlings Central Difference Derivatives
+//Page no. 242
+clc;close;clear;
+printf('   x\t\t    y\t\t    d\t\t    d2\t\t    d3\t\t    d4\n')
+printf('------------------------------------------------------------------------------------------')
+h=0.01;
+a=poly(0,'n');
+deff('y=f3(x)','y=z(x,1)^2*y2(x)+z(x,1)*y1(x)+(z(x,1)^2-a^2)*z(x,2)')
+deff('y=f1(x)','y=(z(x+1,2)-z(x-1,2)-(z(x,4)-z(x-2,4))/factorial(3))/(2*h)')
+deff('y=f2(x)','y=(z(x-1,4)-2*(z(x-2,6))/factorial(4))/h^2')
+z=[85,0.0353878892;85.01,0.0346198696;85.02,0.0338490002;85.03,0.0330753467;85.04,0.032298975];
+for i=3:6
+    for j=1:7-i
+        z(j,i)=z(j+1,i-1)-z(j,i-1)
+    end
+end
+printf('\n')
+for i=1:5
+    for j=1:6
+        if z(i,j)==0 then
+            printf(' \t')
+        elseif j==1
+            printf('   %.2f\t',z(i,j))
+        else
+            printf('%.10f\t',z(i,j))
+        end
+    end
+    printf('\n')
+end
+y1(3)=f1(3);
+y2(3)=f2(3);
+
+printf('\n\ny`(85.02) = %g\n\ny``(85.02) = %.7g\n\n',y1(3),y2(3))
+n=f3(3)
+disp(n,"0 =")
+n=roots(n)
+for i=1:2
+    if abs(n(i))==n(i) then
+        n1=n(i)
+    end
+end
+printf('\n\nn = %.2g',n1)
+\ No newline at end of file