Multiplying By 10000 vs 10^4

Why

A=rand(3,3);
B=A(:)*10000;

is different from

 A=rand(3,3);
 B=A(:)*10^4;

[Stephan]

Hi,

it isnt:

>> A = rand(3,3)

A =

      0.8147    0.9134    0.2785
      0.9058    0.6324    0.5469
      0.1270    0.0975    0.9575

>> B= A(:)*10000

B =

     1.0e+03 *

      8.1472
      9.0579
      1.2699
      9.1338
      6.3236
      0.9754
      2.7850
      5.4688
      9.5751

>> C = A(:)*10^4

C =

     1.0e+03 *

      8.1472
      9.0579
      1.2699
      9.1338
      6.3236
      0.9754
      2.7850
      5.4688
      9.5751

>> Yes_it_is_the_same = B == C

Yes_it_is_the_same =

    9×1 logical array

     1
     1
     1
     1
     1
     1
     1
     1
     1

[Stephan]

the way you wrote it, will generate a new matrix A with new random numbers, which will most likely not be the same as in the first run:

>> clear all
>> A = rand(3,3)

A =

      0.9649    0.9572    0.1419
      0.1576    0.4854    0.4218
      0.9706    0.8003    0.9157

>> B= A(:)*10000

B =

     1.0e+03 *

      9.6489
      1.5761
      9.7059
      9.5717
      4.8538
      8.0028
      1.4189
      4.2176
      9.1574

>> A = rand(3,3)

A =

      0.7922    0.0357    0.6787
      0.9595    0.8491    0.7577
      0.6557    0.9340    0.7431

>> C = A(:)*10^4

C =

     1.0e+03 *

      7.9221
      9.5949
      6.5574
      0.3571
      8.4913
      9.3399
      6.7874
      7.5774
      7.4313

>> Yes_it_is_the_same = B == C

Yes_it_is_the_same =

    9×1 logical array

     0
     0
     0
     0
     0
     0
     0
     0
     0

So you understand the difference between both versions?

bets regards

Answer 1

[Stephan]

See comments, when working with random numbers you have to understand, that everytime you use the command new random numbers will appear - thats the reason why you get different values for the supposed same thing.

Best regards

Stephan