Index exceeds matrix dimensions. Error

This is the error I receive

    _??? Index exceeds matrix dimensions.

Error in ==> CalcPress at 111
    P = pb*((tb/(tb + lb(h - hb)))^(g/(Rs*lb)));

Error in ==> P_2_1_1 at 30
    [P(j),T(j)] = CalcPress(h);_

Script....................

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    istep = 1000;
    imax = 100000;

    h = 0;

    j = 1;
    for i = 0:istep:imax

        h = i;
        [P(j),T(j)] = CalcPress(h); %%%%line 30 %%%%%%

        j = j+1;
    end

Function......

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    Constants;
    EngineSpec;
    FlightChar;

    lb = 0;
    tb = 0;
    pb = 0;
    hb = 0;

    L = [-0.0065,0.0,0.001,0.0028,0.0,-0.0028,-0.002];     %temp lapse rate : K/m

    Ts = [288.15,216.65,216.65,228.65,270.65,270.65,214.65];     %standard temp : K

    Pa = [101325,22632.1,5474.89,868.019,110.906,66.9389,3.95642];   %static pressure : Pa

    H = [0,11000,20000,32000,47000,51000,71000];                       %height at b : meters

    b = [0,1,2,3,4,5,6];

    %%%%%%%%%%Determine proper values of lb, tb, pb, hb  %%%%%%%%%%%%%%%%%%%

    if h <= H(2)

        lb = L(1);
        tb = Ts(1);
        hb = H(1);
        pb = Pa(1);

    end    
    if H(2) <= h <= H(3)

        lb = L(2);
        tb = Ts(2);
        hb = H(2);
        pb = Pa(2);

    end
    if H(3) <= h <= H(4)

        lb = L(3);
        tb = Ts(3);
        hb = H(3);
        pb = Pa(3);

    end    
    if H(4) <= h <= H(5)

        lb = L(4);
        tb = Ts(4);
        hb = H(4);
        pb = Pa(4);

    end    
    if H(5) <= h <= H(6)

        lb = L(5);
        tb = Ts(5);
        hb = H(5);
        pb = Pa(5);

    end    
    if H(6) <= h <= H(7)

        lb = L(6);
        tb = Ts(6);
        hb = H(6);
        pb = Pa(6);

    end    
    if H(7) <= h

        lb = L(7);
        tb = Ts(7);
        hb = H(7);
        pb = Pa(7);

    end    

    %%%%%%%%%%%%%%%%%%%%%%%%%%% Calc Pressure  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    if lb ~= 0

        P = pb*((tb/(tb + lb(h - hb)))^(g/(Rs*lb))); %%%line 111 %%%%

    end
    if lb == 0

        P = pb*exp((-g*(h - hb))/(Rs*tb));

    end

    return;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Any clues on how to fix this error? Appreciate your time and effort!

Answer 1

[Rick Rosson]

Please format your code.

Answer 2

[Matthew]

Is there a certain format in which questions need to be posted in?

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[Rick Rosson]

Thanks!

Answer 3

[Walter Roberson]

In your script, before your line

for i = 0:istep:imax

insert the lines

P = zeros(imax+1,1);
T = zeros(imax+1,1);

[Matthew]

Walter,

I really appreciate the advice, however after amending the program in the way you suggested the error still occurs. Would you happen to have any other ideas?

Thank you kindly,

Matt

[Matthew]

Also,

Does this error state that the initialized P and T vectors are not large enough for the size of the loop? Or that there is a floating point problem that the vectors cannot handle? The prior seemed the most logical, but no matter how large I initialize the receiving vectors the same error occurs. I have never run into this problem before and it is pretty frustrating.

Thanks again,

Matt

[Matthew]

Found the problem in the code body. My equation was not formatted correctly where there should have been a f*(x) there was a f(x.

Answer 4

[Walter Roberson]

Note: your expression

H(2) <= h <= H(3)

will be interpreted as

((H(2) <= h) <= H(3))

The first sub-expression is a logical comparison, false (value 0) or true (value 1). The second comparison would then be comparing that 0 or 1 to H(3).

There is no built-in range comparison operator in MATLAB.

[Matthew]

Thanks Walter, I realized this and added && operators

Answer 5

[Andrei Bobrov]

try variant

% Your Function, input: h 

L = [-0.0065,0.0,0.001,0.0028,0.0,-0.0028,-0.002].';     %temp lapse rate : K/m
Ts = [288.15,216.65,216.65,228.65,270.65,270.65,214.65].';%standard temp : K
% static pressure : Pa
Pa = [101325,22632.1,5474.89,868.019,110.906,66.9389,3.95642].';
H = [0,11000,20000,32000,47000,51000,71000].';        %height at b : meters
b = [0,1,2,3,4,5,6];
[bin,bin] = histc(h,[H(:),inf]);
P = zeros(numel(h),1);
lb = L(bin);
x = [L(bin) Ts(bin), H(bin), pb(bin)];
t1 = lb ~= 0;
t2 = ~t1;
x1 = x(t1,:);
x2 = x(t2,:);
P(t1) = x1(:,4).*((x1(:,2)./(x1(:,2) + x1(:,1).*(h - x1(:,3)))).^(g/(Rs*x1(:,1))));
P(t2) = x2(:,4).*exp((-g*(h - x2(:,3)))./(Rs*x2(:,2)));

% Your Script
h = 0:1e3:1e5;
[P,..] = CalcPress(h);