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

clc
clear
close all
spn=3; %subplot number
spnc=1; 
%Coefficient for Force equations
%Air
Cr=0.12; %drag coefficient of rider
rho=1.168; %density of air (1.256 kg/m^3)
A=1.6; %projected area of the bike and rider(m^2)
%Bump
Pb=12;  %bump power loss coef
%Rolling
Croll=0.08; %Coef or rolling resistance (should be 0.008)
%slope
g=9.81; %m/s^2
%load data
my_data=readmatrix('tt_rider01.xlsx');

Error using readmatrix
Unable to find or open 'tt_rider01.xlsx'. Check the path and filename or file permissions.

Mrider= 163.2 * 0.4536; %convert from lbs to kg
lat=my_data(:,1);
lon=my_data(:,2);
elev=my_data(:,3);
dist=my_data(:,4);
V=my_data(:,6);
subplot(spn,spnc,1)
geoplot(lat,lon)
subplot(spn,spnc,2)
plot(dist,V)
%
for ii=2:length(dist)
    Ddist(ii)=dist(ii)-dist(ii-1);
    VA(ii)=(V(ii)+V(ii-1))/2;
    DV(ii)=V(ii)-V(ii-1);
    Delev(ii)=elev(ii)-elev(ii-1);
    if VA(ii)<=0
        VA(ii)=0.1;
    end
end
Ddist(1)=0.1;
VA(1)=.1;
%Delev(0)=0:.1;
%calculate time steps
for ii=2:length(dist)
    dt(ii)=Ddist(ii)/VA(ii);
    Acc(ii)=DV(ii)/dt(ii);
end
subplot(spn,spnc,3)
plot(Acc)
title('Acceleration')
%Slope angle calculations (in degrees)
for ii=2:length(dist)
    slope(ii)=atand(Delev(ii)/Ddist(ii));
end
subplot(spn,spnc,3)
plot(slope)
%Force calculations
for ii=1:length(dist)
    Fslope(ii)=Mrider*g*sind(ii);
    Fbump(ii)=Pb(ii)/VA(ii); %this line of code is givig me the error
    Froll(ii)=Croll*Mrider*g*cosd(slope(ii));
    Fair(ii)=Cr*A*rho*VA(ii)^2;
    Frider(ii)=Mrider*Acc(ii)+Fslope(ii)+Fbump(ii)+Froll(ii)+Fair(ii);
    Prider(ii)=Frider(ii)*VA(ii);
end
subplot(spn,spnc,5)
plot(Fslope)
title('Fslope')

Answer 1

[Torsten]

Pb is a scalar. So Pb(ii) does not exist.

You can use

Fbump(ii)=Pb/VA(ii); %this line of code is givig me the error

but I don't know that this is what you want.

Answer 2

[chrisw23]

use a try catch block to debug

...

try

Fbump(ii)=Pb(ii)/VA(ii); %this line of code is givig me the error

catch ex

disp(ex.message) % breakpoint here and debug your variables and indices

end

...