Calling a function in itself.

I have a long code that uses two indices to update the resistance values in a powerflow program as below. The powerflow program is described by the function

[alphaN,betaN,V_feeder,fdr_HC,VI_out,VA,VB,VC,VUB,IA,IB,IC]= start_f7(1,1,1,1,fdrcon,sheetname,fdrpath1);

The rest of the code is as below - and it basically locates and updates the inputs.

function[NewRC,NewAmpC,NewR,NewAmp,NPI,CPI,R]=Adjustingcode2(fdrpath1,sheetname,RepCondpath)
tic;
fname1 =  fdrpath1; sheet = sheetname; ResRange1 = "G6:G12"; AmpRange="AG6:AG12"; 
fdrcon_range="AK6:AM60";fdrcon = xlsread(fdrpath1, sheetname,fdrcon_range);
[alphaN,betaN,V_feeder,fdr_HC,VI_out,VA,VB,VC,VUB,IA,IB,IC]= start_f7(1,1,1,1,fdrcon,sheetname,fdrpath1);
R=xlsread(fname1,sheet,ResRange1); Amp=xlsread(fname1,sheet,AmpRange);

%% Branch and node performance - calculating replacement

[Vmax,Imax]=BNPerf(VA,VB,VC,IA,IB,IC);
[NPI,CPI,OptiCR_1, OptiVR_2] = NCL_recon(Vmax,Imax,fdrpath1,sheetname);

fname2 = RepCondpath; 
sheet1 = 3;Range = "G2:G15";
TAmpRange = "I2:I15";  TR=xlsread(fname2,sheet1,Range); TAmp= xlsread(fname2,sheet1,TAmpRange);

i = 1;
while i <= size(R, 1)
    j = 1;
    while j <= size(TR, 1)
        if CPI(i) < 1
            NewRC(i) = R(i);
            NewAmpC(i) = Amp(i);
            break;
        elseif CPI(i) > 1
            if TR(j) <= OptiCR_1(i)
                NewRC(i) = TR(j);
                NewAmpC(i) = TAmp(j);
                break;
            end
        end
        j = j + 1;
    end
    i = i + 1;
end

i=1;
while i<= size(R,1)
    j=1;
    while  j<=size(TR,1)
        if NPI(i)<1
            NewR (i)= NewRC(i);
            NewAmp (i) =NewAmpC(i);
            break
        elseif NPI(i)>1
            if TR(j)<=OptiVR_2(i)                     % original was R
                NewR(i)= TR(j);
                NewAmp(i) =TAmp(j);
                break
            end
        end
        j=j+1;
    end
    i=i+1;
end

xlswrite(fname1,NewR.',sheet,ResRange1)
xlswrite(fname1,NewAmp.',sheet,AmpRange)

Up to this point, my code works fine. So, I would like to do this repeetively till when my indices NPI and CPI are both compliant. I have written the following as the code to check if each of the indices meets the threshold and to recurse the program but it does not seem to be updating. Can someone help me see where the bug is?

option 1 using the while loop

%% option 1 using the while loop
[NPI, CPI, OptiCR, OptiVR] =  NCL_recon(Vmax,Imax,fdrpath1,sheetname);
k = 1;
while k <= length(CPI)
    if CPI(k) > 1
        [NewRC, NewAmpC, NewR, NewAmp, NPI, CPI, R] = Adjustingcode2(fdrpath1, sheetname, RepCondpath);
    end
    if NPI(k)>1
        [NewRC, NewAmpC, NewR, NewAmp, NPI, CPI, R] = Adjustingcode2(fdrpath1, sheetname, RepCondpath);
    end
    k = k + 1;
end
[~,~,~,~,~,VA,VB,VC,~,IA,IB,IC]=start_f7(1,1,1,1,fdrcon,sheetname,fdrpath1);
PL=size(IA,3);
toc;

[Vmax,Imax]=BNPerf(VA,VB,VC,IA,IB,IC);

option 2 using the for loop and OR

[NPI, CPI, OptiCR, OptiVR] = NCL_recon(Vmax, Imax, fdrpath1, sheetname);

for k = 1:length(CPI)
    if CPI(k) > 1 || NPI(k) > 1
        [NewRC, NewAmpC, NewR, NewAmp, UpdatedNPI, UpdatedCPI, R] = Adjustingcode2(fdrpath1, sheetname, RepCondpath);
        NPI(k) = UpdatedNPI;
        CPI(k) = UpdatedCPI;
    end
end
[~,~,~,~,~,VA,VB,VC,~,IA,IB,IC]=start_f7(1,1,1,1,fdrcon,sheetname,fdrpath1);
PL=size(IA,3);
toc;

[Vmax,Imax]=BNPerf(VA,VB,VC,IA,IB,IC);

Any help will be appreciated.

[YASSINE]

Hi, if you want to create a recursive function, you should call it with different arguments; otherwise, you might create an infinite loop.

Answer 1

[Steven Lord]

It is possible to recursively call a function in MATLAB (within reason, there is a recursion limit in MATLAB to try to prevent your code from getting into an infinite loop and possibly crashing MATLAB and/or your computer.) In your code I see your "recursive step" but it's not clear to me what your "base case" is (using the terms from the Wikipedia page.)

y = factorial2014476(10)

Recursive case, calling function with 9.
Recursive case, calling function with 8.
Recursive case, calling function with 7.
Recursive case, calling function with 6.
Recursive case, calling function with 5.
Recursive case, calling function with 4.
Recursive case, calling function with 3.
Recursive case, calling function with 2.
Recursive case, calling function with 1.
Recursive case, calling function with 0.
Base case, n = 0

y = 3628800

check = factorial(10) % using the function included in MATLAB

check = 3628800

factorial2014476(0)

Base case, n = 0

ans = 1

factorial(0)

ans = 1

function F = factorial2014476(n)
arguments
    n (1, 1) {mustBeNonnegative, mustBeInteger} % error checking
end
if n == 0
    fprintf("Base case, n = 0")
    F = 1; % base case, does not call the function recursively
else
    fprintf("Recursive case, calling function with %d.\n", n-1)
    F = n*factorial2014476(n-1); % recursive step, does call the function recursively
end
end

So under what circumstances does your function not call itself?

[Lewis Waswa]

It does. The problem is that it does so recursively and does not update the input file in the excel sheet.