how velocize operation boolean

N = 5

N = 5

a=[0.3 1 0 3 9]

a = 1×5

0.3000 1.0000 0 3.0000 9.0000

b=a<N

b = 1×5 logical array
   1   1   1   1   0

find(b&(~a))

ans = 3

Answer 1

[Image Analyst]

That code has nothing to do with your subject line. You want

logicalIndexes = a == 1
% or
linearIndexes = find(a == 1)

Same for b or any other variable.

[pipor]

i want find index

a=[5 0 1 9 0]

n=6;

a===> [1 0 1 1 0]

b==> a-n=[1 1 1 0 1]

(i want to find idx element that change from 0 to 1 )

0 1 0 0 solution ! ==> 2 position

[Dyuman Joshi]

How is a-n equal to what you have wrote?

n=6;
a=[1 0 1 1 0];
b=a-n

b = 1×5

-5 -6 -5 -5 -6

[pipor]

sorry I was wrong..but I did the numerical example by hand

b=n-a

[pipor]

a=[0.3 1 0 3 9]

a = 1×5

0.3000 1.0000 0 3.0000 9.0000

n=6

n = 6

b=a<n

b = 1×5 logical array
   1   1   1   1   0

a>0

ans = 1×5 logical array
   1   1   0   1   1

b

b = 1×5 logical array
   1   1   1   1   0

find((a==0)&(~b==0))

ans = 3

[Walter Roberson]

a=[0.3 1 0 3 9]

a = 1×5

0.3000 1.0000 0 3.0000 9.0000

n=6

n = 6

b=a<n

b = 1×5 logical array
   1   1   1   1   0

a>0

ans = 1×5 logical array
   1   1   0   1   1

b

b = 1×5 logical array
   1   1   1   1   0

find((a==0)&(~(b==0)))

ans = 3

but with b already being logical, b==0 is the same as ~b, and ~ of that is ~~b which for logical would be the same as b

Answer 2

[Image Analyst]

You asked : "(i want to find idx element that change from 0 to 1 )"

So do this:

a = [5, 0, 1, 9, 0, 1];
index = strfind(a, [0, 1]) % Look for where [0, 1] occurs in the vector.

index = 1×2

2 5

The index is at the start, that is, where the zeros are.

[pipor]

how could you verify I have problems speaking English correctly..but you insist on helping me with a solution that I didn't ask for..now I've changed the topic so you're more serene

[Image Analyst]

" i want find element that: a==0 and b==1"

Try this:

a= [1 1 0 1 1]; %   (is correct)
b = [1 1 1 1 0];  % (is correct)
logicalIndexes = (a == 0) & (b == 1)

logicalIndexes = 1×5 logical array
   0   0   1   0   0

linearIndexes = find((a == 0) & (b == 1))

linearIndexes = 3

This should all be covered in the learning on-ramp. To learn other fundamental concepts, invest 2 hours of your time here:

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[pipor]

ok solved..thanks

[pipor]

excuse me a last question:

you use: (b == 1)) but b is logical

why you don't use (b) ..is the same?

[Image Analyst]

(b == 1) will be logical because it's comparing the number to 1. b can be any data type, like double or integer or logical. The result will be true or false values, or 1 and 0 if you convert them to numbers, for example to multiply element-by-element by another numerical vector.

If b is logical than (b) is logical (already). If b is a double vector like [1,2,44,66] then b is not logical -- not true or false values.