MATLAB: How to make variables in a while loop be an array

arrayvariableswhile loop

Could anybody help me with this please? I am trying to work out a optimisation problem. I am using a while loop. I am able to obtain results in an array e.g. result(n).however, I am not able to make variable "n" as an array,hence, the value that I can access is always the last n value appeared. I would like to know how to make the variables into an array form that I can access the optimal result,aslo the corresponding variable "n" value.

Best Answer

idx = 0;
while ....
  n = ....
  result(n) = ....
  idx = idx + 1;   %!

  all_n(idx) = n;  %!
end

Then later you can (for example)

for K = 1 : idx
  this_n = all_n(idx);
  disp(result(this_n))
end

Related Solutions

MATLAB: Get while loop answer as a vector

n = 12;
while n>1
   if mod(n(end),2)==0
      n(end+1)=n(end)/2;
   else
      n(end+1)=3*n(end)+1;
   end    
end

creates this vector:

>> n
n =
    12     6     3    10     5    16     8     4     2     1

Note that this is not a very good way to write MATLAB code, because it expands the array in each loop iteration (clearly highlighted with a warning in the MATLAB editor!):

http://www.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html

MATLAB: Hello i have an iteration table for a maclaurin series, can anyone tell me what’s the coding to make a table like this

There are several ways to calculate a series in MATLAB. From your question, you appear to be a beginner, so I will show an intuitive way using for-loop.

term_n = @(x,n) x^n./factorial(n); % formula for n-th term of series
N = 10; % total number of terms we are going to calculate
result = zeros(1,N+1); % initializng a array to save the partial sums
eplison_t = zeros(1,N+1);
eplison_a = zeros(1,N+1);
x = 1/2; % value of x to use in this calculation
result(1) = term_n(x,0); % calculate first term of the series at n=0
eplison_t(1) = (exp(x) - result(1))/exp(x);
for n=1:N % terms n=1,2,...,N
    result(n+1) = result(n) + term_n(x,n); % current partial sum is the addition of last partial sum and the value of n-th term
    eplison_t(n+1) = (exp(x) - result(n+1))/exp(x);
    eplison_a(n+1) = (result(n+1)-result(n))/result(n+1);
end
eplison_t = 100*eplison_t;
eplison_a = 100*eplison_a;
t = table(result', eplison_t', eplison_a');
disp(t)

Result

>> test_fun
     Var1        Var2          Var3   
    ______    __________    __________
         1        39.347             0
       1.5        9.0204        33.333
     1.625        1.4388        7.6923
    1.6458       0.17516        1.2658
    1.6484      0.017212       0.15798
    1.6487     0.0014165      0.015795
    1.6487    0.00010024     0.0013163
    1.6487    6.2197e-06    9.4018e-05
    1.6487    3.4355e-07    5.8761e-06
    1.6487    1.7097e-08    3.2645e-07
    1.6487     7.741e-10    1.6323e-08

Best Answer

Related Solutions

MATLAB: Get while loop answer as a vector

MATLAB: Hello i have an iteration table for a maclaurin series, can anyone tell me what’s the coding to make a table like this

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