Index exceeds the number of array elements. Index must not exceed 1.

Could you please help me to solve the problem. I'm trying to calculate the difference between heights in a loop.

But it gives error "Index exceeds the number of array elements. Index must not exceed 1."

My code is

clear all; close all

W = 10000;
S = 40;
AR = 7;
cd0 = 0.005;
k = 1 / pi / AR;
j=0;
hv=6:-.01:0;
figure(1);hold on; xlabel('h');ylabel('V')
for h1=6:-.01:0
    j=j+1;
    cdminp=4*cd0;
    rho1(j)=1.225*exp(-h1/10.4);
    clminp=sqrt(3*cd0/k);
    Vminp(j)=sqrt(2*W/rho1(j)/S/clminp);
    dh(j)=h1(j)-h1(j+1);
end
figure(1); plot(hv, Vminp);
set(gca, 'XDir','reverse');

[Dyuman Joshi]

In the last line of the for loop

dh(j)=h1(j)-h1(j+1)

h1 is the loop index, it has only one value at a time.

What is it that you are trying to do by this line of code? Or did you by mistake mistype the variable?

[Sarvesh Kale]

Hi Alina Abdikadyr

@Dyuman Joshi is correct

Does this code help ?

W = 10000;
S = 40;
AR = 7;
cd0 = 0.005;
k = 1 / pi / AR;
j=0;
hv=6:-.01:0;
figure(1);hold on; xlabel('h');ylabel('V')

for h1=6:-.01:0
    j=j+1;
    cdminp=4*cd0;
    rho1(j)=1.225*exp(-h1/10.4);
    clminp=sqrt(3*cd0/k);
    Vminp(j)=sqrt(2*W/rho1(j)/S/clminp);
end

figure(1); plot(hv, Vminp);
set(gca, 'XDir','reverse'); 

dh=diff(hv);

If you are trying to calculate the difference between consecutive elements in array have a look at diff function documentation https://in.mathworks.com/help/matlab/ref/diff.html .

[Alina Abdikadyr]

Thank you! I want to calculate the difference between the first element and the folloing elements.

If my h1=6:-.01:0

Probably I should write as:

dh=h1(1)-h1(j+1);

so I need to get the values of dh = 0.01;0.02;0.03;0.04 and so on

[Les Beckham]

If you know what the h1 vector is already, you don't need a loop to calculate the accumulated difference between elements of it.

h1=6:-.01:0;
dh = -cumsum(diff(h1));
dh(1:10) % look at the first ten elements

ans = 1×10

0.0100 0.0200 0.0300 0.0400 0.0500 0.0600 0.0700 0.0800 0.0900 0.1000

Answer 1

[Dyuman Joshi]

You can do that without the loop

W = 10000;
S = 40;
AR = 7;
cd0 = 0.005;
k = 1 / pi / AR;
hv = 6:-.01:0;

cdminp = 4*cd0;
clminp = sqrt(3*cd0/k);

rho1 = 1.225.*exp(-hv./10.4);
Vminp = (2.*W./rho1./S).^(1/2);
dh = hv(1)-hv(2:end)

dh = 1×600

0.0100 0.0200 0.0300 0.0400 0.0500 0.0600 0.0700 0.0800 0.0900 0.1000 0.1100 0.1200 0.1300 0.1400 0.1500 0.1600 0.1700 0.1800 0.1900 0.2000 0.2100 0.2200 0.2300 0.2400 0.2500 0.2600 0.2700 0.2800 0.2900 0.3000

figure(1);
hold on;
xlabel('h');ylabel('V')
plot(hv,Vminp)
set(gca, 'XDir','reverse');