How to keep only 3 digits after the dot on a number?

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Nick 2021-5-6

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评论： Chunru 2021-5-11

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Hello

I have an array (1000x11) of binary numbers like this :

 0   1   1   0   0   0   1   1   0   0
 0   0   1   0   1   1   0   1   0   0
 1   1   0   1   1   0   1   1   0   0
 0   0   1   1   0   1   1   0   1   1
 1   0   1   0   1   0   0   1   1   1
 1   0   0   1   0   0   0   0   0   1
 0   0   0   1   0   1   1   0   0   0
 0   1   0   0   0   1   1   0   1   0

And I want to turn each row into a float decimal (x) with the last 10 binary digits as the numbers after the dots. I did this:

x = x(:, 1) + (x(:, 2:11) * 2.^(9:-1:0).') / 1000

but I got :

x = 1.8260
x =0.1110
x =1.9900
x =1.1640
x =0.3050
x = 0.6640

and I get the error 'Index exceeds matrix dimensions' so I have to take only the first 3 digits after the dot. How do I do that?

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James Tursa 2021-5-7

编辑：James Tursa 2021-5-7

What would help us is for you to give us a description of inputs and desired outputs, with some small examples. E.g.,

"I am starting with these binary digits 101101001 and I want to do calculations that turn it into the floating point number ___."

(you fill in this blank for us)

Nick 2021-5-7

编辑：Nick 2021-5-7

"I am starting with these binary digits 10110001100 and I want to do calculations that turn it into the floating point number 1.396 ."

Could you also please check the files I attached? Maybe the mistake is there

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回答（1 个）

Chunru 2021-5-7

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https://ww2.mathworks.cn/matlabcentral/answers/823740-how-to-keep-only-3-digits-after-the-dot-on-a-number#answer_693920

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Try the following:

x = randi([0 1], 4, 11) 
%x = x(:, 1) + (x(:, 2:11) * 2.^(9:-1:0).') / 1000 ;     % May not accurate
x = x * 2.^(0:-1:-10)'              % This is the binary value