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Only axes are appearing but plot is not showing. Please help me to detect the error i am making in the program. Apologies for a long code.

clear all; close all; clc;

test_points=3;

start_point=1000;

x_rec(1)=x(start_point);

x_real(1)=x(start_point);

c1=ksaix(1);

c2=ksaix(2);

c3=ksaix(3);

c4=ksaix(4);

c5=ksaix(5);

c6=ksaix(6);

c7=ksaix(7);

c8=ksaix(8);

c9=ksaix(9);

c10=ksaix(10);

c11=ksaix(11);

c12=ksaix(12);

c13=ksaix(13);

c14=ksaix(14);

c15=ksaix(15);

c16=ksaix(16);

c17=ksaix(17);

c18=ksaix(18);

c19=ksaix(19);

c20=ksaix(20);

c21=ksaix(21);

c22=ksaix(22);

c23=ksaix(23);

c24=ksaix(24);

c25=ksaix(25);

error=0;

DN=0;

for i=4:test_points

x_rec(i)=c1+c2*x_rec(i-1)+c3*x_rec(i-1)^2+c4*x_rec(i-1)^3+c5*x_rec(i-1)^4+c6*x_rec(i-1)^5+c7*x_rec(i-1)^6+c8*x_rec(i-1)^7+c9*x_rec(i-1)^8+c10*x_rec(i-1)^9+c11*x_rec(i-1)^10+c12*x_rec(i-1)^11+c13*x_rec(i-1)^12+c14*x_rec(i-1)^13+c15*x_rec(i-1)^14+c16*x_rec(i-1)^15+c17*x_rec(i-1)^16+c18*x_rec(i-1)^17+c19*x_rec(i-1)^18+c20*x_rec(i-1)^19+c21*x_rec(i-1)^20+c22*x_rec(i-1)^21+c23*x_rec(i-1)^22+c24*x_rec(i-1)^23+c25*x_rec(i-1)^24;

error=error+(x_rec(i)-x_real(i))^2;

DN=DN+x_real(i)^2;

end

Error_x(count)=sqrt(error)/sqrt(DN);

end

figure

hold on

plot (Data,Error_x,'s-r')

dpb
on 17 Oct 2020

As for the original question, anything that uses a polynomial to the 24th power is just asking for numerical troubles--either over- or underflow and imprecision.

As another said, probably you're ending up with NaN or Inf as results.

Image Analyst
on 17 Oct 2020

Look at the first few lines:

clear all; close all; clc;

test_points=3;

start_point=1000;

x_rec(1)=x(start_point);

Now you try to get x(start_point) but you never defined it. SO that throws an error. Or if you did (in another script), you blew it away with the clear all command.

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