dividing defined variable by named variable

everytime i try to divide a defined variable by a calculated variable, it only outputs one number multiple times. What syntax am i missing?

d=1:.2:3;

a=sqrt((d.^2)*(3^2));

Y=d./a

[Stephen23]

" it only outputs one number multiple times."

Because that is the correct result for your code, which is equivalent to d./(3*d)

"What syntax am i missing?"

Because you did not state the expected output nor what you are trying to achieve, we cannot guess the syntax that is required to achieve an unstated goal.

Answer 1

[Image Analyst]

Well yeah. Just look at the numbers:

d = 1 : 0.2 : 3

d = 1×11

1.0000 1.2000 1.4000 1.6000 1.8000 2.0000 2.2000 2.4000 2.6000 2.8000 3.0000

a = sqrt((d.^2)*(3^2))

a = 1×11

3.0000 3.6000 4.2000 4.8000 5.4000 6.0000 6.6000 7.2000 7.8000 8.4000 9.0000

Y = d ./ a

Y = 1×11

0.3333 0.3333 0.3333 0.3333 0.3333 0.3333 0.3333 0.3333 0.3333 0.3333 0.3333

They all look right to me. Exactly what output numbers did you expect? Tell me which element of Y it got wrong and should be a different number.

[Liam Bates]

I needed the values for Y to be different. a different value for every different value of d.

[Liam Bates]

is it just how the matrix is set up? would i need a loop instead?

[Image Analyst]

You can define "a" differently then, like perhaps add noise

d = 1 : 0.2 : 3

d = 1×11

1.0000 1.2000 1.4000 1.6000 1.8000 2.0000 2.2000 2.4000 2.6000 2.8000 3.0000

a = sqrt((d.^2)*(3^2)) + rand(size(d))

a = 1×11

3.3071 4.0240 4.6150 5.2096 5.6304 6.3306 7.5081 8.0647 7.8299 8.5545 9.7844

Y = d ./ a

Y = 1×11

0.3024 0.2982 0.3034 0.3071 0.3197 0.3159 0.2930 0.2976 0.3321 0.3273 0.3066

Answer 2

[Walter Roberson]

a=sqrt((d.^2)*(3^2))

3^2 is 9 so inside the sqrt() you have 9*d^2. sqrt() of that is sqrt(9)*sqrt(d^2). For positive d that is 3*d

Y = d ./ a

So you have d divided by 3*d. For non-zero d that is going to be 1/3 no matter what the positive value of d is. For negative d you would get -1/3. For 0 you get nan.