Array indices must be positive integers or logical values.

symbol = {'1','2','3','4','5','6','7','8','9','*','0','#'};

lowFreqGroup = [697, 770, 852, 941]; %frequencies in rows

highFreqGroup = [1209, 1336, 1477]; %frequencies in columns

freqArray = [];

for i = 1:4

for j = 1:3

freqArray = ([lowFreqGroup(i); highFreqGroup(j)]); %create pairs

end

end

Fs = 8e3; %sampling frequency

N = 8e2; %tones of 100ms

t = (0:N-1)/Fs; %time

sine = 2*pi*t; %sine formula

toneArray = zeros(N, size(freqArray,2)); %array of N*12 for graph

for i = 1:12 %loop for each of 12 symbols

toneArray(:,i) =sum(sin(freqArray(:,i)*sine)); %make it sinusoidal

subplot(4,3,i);

[Stephen23]

Duplicate:

https://www.mathworks.com/matlabcentral/answers/815200-array-indices-must-be-positive-integers-or-logical-values

Answer 1

[Star Strider]

There were problems with indexing ‘freqArray’ and then ‘toneArray’.

See if this does what you want —

symbol = {'1','2','3','4','5','6','7','8','9','*','0','#'};
lowFreqGroup = [697, 770, 852, 941]; %frequencies in rows
highFreqGroup = [1209, 1336, 1477]; %frequencies in columns
freqArray = [];
for i = 1:4
    for j = 1:3
        freqArray(:,i,j) = ([lowFreqGroup(i); highFreqGroup(j)]); %create pairs
    end
end
Fs = 8e3; %sampling frequency
N = 8e2; %tones of 100ms
t = (0:N-1)/Fs; %time
sine = 2*pi*t; %sine formula
toneArray = zeros(N, size(freqArray,2)); %array of N*12 for graph
for i = 1:12 %loop for each of 12 symbols
    ii = ceil(i/3);
    jj = ceil(i/4);
    toneArray(:,i) =sum(sin(freqArray(:,ii,jj)*sine)); %make it sinusoidal
    subplot(4,3,i)
    plot(t, toneArray(:,i))
    grid
    title(sprintf('Symbol: %s',symbol{i}))
end

I will let you discover the changes I made to the code, and how they work.