Argggh! My equation isn't plotting right with a for loop!!!

Greetings all,

This is probably trivial and overlooking a minor detail, but I have the following code, and I think my problem is that I have to start at zero somewhere:

Response_values= 0:0.1:2;
phiv=zeros(size(Response_values));

for n=1:length(Response_values)
    if Response_values(n)<2.1
        phiv(n)=(4*n)/((4*n.^2+1).^3/2)
    else
        phiv(n)=0;
    end
end

plot(Response_values,phiv);

As it is right now, "n" isn't being indexed right, therefore my plot is wrong. I know as of right now it starts at 1 and goes to 21. I wanted the equation to go from 0 to 2 in .1 increments. I know in MATLAB you can't start at an index of zero, so I searched these boards and tried to code the above.

Any help would be appreciated.

Thanks! -J

Answer 1

[Image Analyst]

Try this:

Response_values= 0:0.1:2;
phiv=zeros(size(Response_values));

for n=1:length(Response_values)
  rValue = Response_values(n);
    if rValue < 2.1
        phiv(n)=(4*rValue)/((4*rValue.^2+1).^3/2)
    else
        phiv(n)=0;
    end
end

plot(Response_values,phiv);
grid on;
xlabel('Response Value', 'FontSize', 20);
ylabel('phiv', 'FontSize', 20);

[Jesse]

Yes! Thank you so much!!!!