Generating array of data using for-end looping

I want to generate an array of number using for-end, i know that I can generate logarithmic series using logspace, but in this case, i can't use that

so I run this code:

function y=generate
for i=1:20
    j(i)=10^((i-1)/2);

      for l=1:5;
      y(l)=j(i)+l/5*j(i)*sqrt(10);
      end   

end
result1=[y'];

my expectation is that I can generate logarithmic series of 100 number from 10^0 to 10^9.5, but instead getting 100 numbers, I run it and only get these:

ans =

    1.0e+010 * 

      0.5162    0.7162    0.9162    1.1162    1.3162

then what should I do to get the 100 numbers, I need the '20' on 'i=1:20' in other function, that's why i can't use logspace because logspace can't be use inside looping command (for-end). Please I need your advice and I am just a beginner.

I appreciate your help

Answer 1

[Paulo Silva]

result1=zeros(1,100);p=1; %create a vector to save the values and the index
for i=1:20
    j(i)=10^((i-1)/2);
      for l=1:5;
      y(l)=j(i)+l/5*j(i)*sqrt(10);
      result1(p)=y(l); p=p+1; %save current value and increment index
      end   
end

result1; %your vector with the values

I didn't check if the values are correct, just plot(result1) and it does look like something logarithmic

Edit: You can't use the logspace function but maybe you can steal the logspace code ;)

d1=0;d2=9.5;n=100;
result1 = (10).^ [d1+(0:n-2)*(d2-d1)/(floor(n)-1), d2];

Answer 2

[Matt Fig]

Another non-loop alternative (edit logspace):

mylogspace = @(x1,x2,n) 10.^ [x1+(0:n-2)*(x2-x1)/(n-1), x2]
mylogspace(0,9.5,100)

Here is how to do it in a loop:

function y = generate

cnt = 0;
y = zeros(1,100);  % Pre-allocate

for ii = 1:19/99:20
    cnt = cnt + 1;
    y(cnt) = 10^((ii-1)/2);
end

Or in general:

function y = generate(x1,x2,n)
% Generates logspace(x1,x2,n)
cnt = 0;
y = zeros(1,n);

for ii = x1:(x2-x1)/(n-1):x2
    cnt = cnt + 1;
    y(cnt) = 10^ii;
end

Answer 3

[Andrei Bobrov]

all without logspace

[jj,ll] = meshgrid(1:20,1:5);
result2 = reshape(10.^((jj-1)/2).*(1+ll/5*sqrt(10)),1,[]);

or

result2 = reshape(bsxfun(@(jj,ll)10.^((jj-1)/2).*(1+ll/5*sqrt(10)),1:20,(1:5)'),1,[]);