Multiplying By 10000 vs 10^4

Question

Harel Harel Shattenstein 2018-4-27

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/397770-multiplying-by-10000-vs-10-4

编辑： Stephan 2018-4-27

Why

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

is different from

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

2 个评论
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Stephan 2018-4-27

在 MATLAB Online 中打开

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 2018-4-27

编辑：Stephan 2018-4-27

在 MATLAB Online 中打开

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

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Answer 1

Stephan 2018-4-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/397770-multiplying-by-10000-vs-10-4#answer_317550

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