array indices and bisector method

Hello,

I'm trying to find a root using the bisector method, using two functions I've made in previous files. Those functions are [PForce, LoadingDuration]= myfunction(x) and [z]= PFunction (m,k,x). I replaced the x by xL, xM and xU which are the values used to calculate the root. Each time I run it it says

Array indices must be positive integers or logical values.

Error in exercice2 (line 10)
    z(xL) = PDFunction (m,k,xL);
    

I'm not really sure how to correct this so if anyone know i'd be happy to know !! Thanks a lot

Here is the full code:

    clc;clear;
m=800; k=1e6;
xL=0; xU= 10; Difference=1;
tstep=0.0001;
while Difference > 0.0005
    xM = (xU-xL)/2;
    [PForceL,LoadingDurationL] = myfunction(xL);
    [PForceU,LoadingDurationU] = myfunction(xU);
    [PForceM,LoadingDurationM] = myfunction(xM);
    z(xL) = PDFunction (m,k,xL);
    z(xU) = PDFunction (m,k,xU);
    z(xM) = PDFunction (m,k,xM);
    MaxdL= max(deflectionL);
    MaxdU= max(deflectionU);
    MaxdM= max(deflectionM);
    
    if MaxdM > 0.1
        xL=xM;
    else
        xU=xM;
    end
    Difference = abs(MaxdM-0.1);
end

Answer 1

[James Tursa]

It is not clear what z is supposed to be used for in these lines:

    z(xL) = PDFunction (m,k,xL);
    z(xU) = PDFunction (m,k,xU);
    z(xM) = PDFunction (m,k,xM);

You could simply delete these lines.

It is also not clear where the deflection variables are defined.

[James Tursa]

So could you just do this?

 [deflectionL,tL]= PDFunction (PForceL,k,m,LoadingDurationL);
 [deflectionU,tU]= PDFunction (PForceU,k,m,LoadingDurationU);
 [deflectionM,tM]= PDFunction (PForceM,k,m,LoadingDurationM);