Getting rid of for loop in one-liner code

Lets assume we have an optimization problem like this:

x = zeros(1,10);
x(1,1) = 2;
for k = 1: 9
    x(k+1) = 10 x(k);
end

Is it possible to write the equation without the for loop?

Answer 1

[John BG]

Sakil

ok for a matrix, look:

    A=[1 2;3 4];n=[1:1:10];L=A(:);B=reshape(bsxfun(@power,L,n),[size(A),10])

the resulting exponential matrices are stored in the layers of B

    B(:,:,1) =
         1     2
         3     4
    B(:,:,2) =
         1     4
         9    16
    B(:,:,3) =
         1     8
        27    64
    B(:,:,4) =
         1    16
        81   256
    B(:,:,5) =
               1          32
             243        1024
    B(:,:,6) =
               1          64
             729        4096
    B(:,:,7) =
               1         128
            2187       16384
    B(:,:,8) =
               1         256
            6561       65536
    B(:,:,9) =
               1         512
           19683      262144
    B(:,:,10) =
               1        1024
           59049     1048576

.

Sakil

would you please be so kind to mark my answer as Accepted Answer,

thanks in advance

regards

John BG

<mailto:[e-mail] [e-mail]>

Answer 2

[John BG]

this

x = zeros(1,10);
x(1) = 2;
for k = 1: 9
    x(k+1) = 10 *x(k);
end

x
 =
  Columns 1 through 3
          2.00         20.00        200.00
  Columns 4 through 6
       2000.00      20000.00     200000.00
  Columns 7 through 9
    2000000.00   20000000.00  200000000.00
  Column 10
 2000000000.00

is the same as

n=[1:1:10];x=.2*10.^n
x =
  Columns 1 through 3
          2.00         20.00        200.00
  Columns 4 through 6
       2000.00      20000.00     200000.00
  Columns 7 through 9
    2000000.00   20000000.00  200000000.00
  Column 10
 2000000000.00

if you find this answer useful would you please be so kind to mark my answer as Accepted Answer?

To any other reader, please if you find this answer of any help solving your question,

please click on the thumbs-up vote link,

thanks in advance

John BG

<mailto:[e-mail] [e-mail]>

[Sakil Chowdhury]

Hi. What if the multiplier is not 10? say the multiplier is a 2 by 2 matrix A. Then the statement will be:

x = x(1) * (A.^(0:9));

but this seems to be not working. Can you please check that?

[Walter Roberson]

More compactly,

    x = 2 * 10.^(0:9);

[Jan]

@Sakil: The operation A.^(0:9) is not valid, therefore the readers have to guess, what you want as result. Which dimension does x have after this calculation?