How to solve this error for the calculation of PVmax2? : Array indices must be positive integers or logical values.

Af= 0.5 ;

Vmax = 33.3333; % Vehicle maximum Speed: 120 Km/h

VGmax= 5.55556; % Vehicle maximum speed at maximum grade (30 degrees)

Vcr = 22.2222; % Crusing Speed : 80 km/h

Mw = 1300;

g = 9.81;

row = 1.1; % Air Density

Cd = 0.0145; % coefficient of drag

mue = 0.015;

alpha = 0;

PVmax1 = (0.5 * row * Cd * Af *(Vmax^2)) + (Mw*g*Vmax(cos(alpha)+ (mue*sin(alpha))));

P1 = ['Average Power to maintain maximum speed = ',num2str(PVmax1), ' Watts'];

disp(P1)

GMax = 30; % maximum vehicle grade

PVmax2 = (0.5 * row * Cd * Af *(VGmax^2)) + (Mw*g*VGmax(cos(GMax)+ (mue*sin(GMax))));

P2 = ['Maximum power at Maximum Grade = ',num2str(PVmax2), ' Watts'];

disp (P2)

Answer 1

[Star Strider]

My guess is that you’re missing an operator (possibly a ‘*’ for multiplication) here (note ↑):

PVmax1 = (0.5 * row * Cd * Af *(Vmax^2)) + (Mw*g*Vmax(cos(alpha)+  (mue*sin(alpha))));
                                                     ↑

and:

PVmax2 = (0.5 * row * Cd * Af *(VGmax^2)) + (Mw*g*VGmax(cos(GMax)+  (mue*sin(GMax))));
                                                       ↑

Anyway, when I insert asterisks in thole locations, your code runs.

[Ryan Cummings]

Thanks man, it worked

[Star Strider]

As always, my pleasure.