Extract a range of frequencies and power from X-Y vector/array

Hello,

I hope you are in good health.

I am trying to select a range of frequencies and their corresponding power from the given data set.

load phaseNoise.mat
plot(fnew,pnew)

xRange_new = fnew(fnew == 10e+009 | fnew <= 30e+009);
x_index = find (fnew == xRange_new);

Arrays have incompatible sizes for this operation.

yRange_new = pnew(x_index);
plot(xRange_new, yRange_new)

However, I get an error when I try to find the indexes of the specific frequencies saying that 'Arrays have incompatibel sizes for this operation.'. I know that the array sizes are different but I want to know how can I extract the x and y values simultaneously. I can use the zoom feature to only display the part I want but that's not what I want.

(If finding the indexes of the x values are not necessary then guide me on achieving the desired results so...)

Basically, I want to only select the frequencies from 10GHz to 30GHz and their corresponding Y-values and discard the rest of the values so I can display the graph from 10GHz to 30GHz and perform further analysis on the given range only.

Any help will be appreciated.

BR.

Answer 1

[Mathieu NOE]

hello

some minor bugs , see comments

this is what you wanted :

load phaseNoise.mat
plot(fnew,pnew)

x_index = (fnew >= 10e+009 & fnew <= 30e+009); %  & , not | !!; also, logical indexing suffices , no need to use "find"
xRange_new = fnew(x_index);
yRange_new = pnew(x_index);
plot(xRange_new, yRange_new)

[Sibghat]

Thank you for the corrections.

Yes, this is what I wanted. However, the x_index is returning a logical array with 0s and 1s only. Therefore, can you simplify how the xRange_new = fnew(x_index) and yRange_new = pnew(x_index) are extracting the values from the given arrays because it is either fnew(0) or fnew(1).

Thanks once again...

[Mathieu NOE]

hello

I am not sure to understand what you mean by "simplify" in your sentence :

Therefore, can you simplify how the xRange_new = fnew(x_index) and yRange_new = pnew(x_index) are extracting the values from the given arrays because it is either fnew(0) or fnew(1).

using logical index means that xRange_new will contain only the "valid" fnew data (valid here means where the logical index is non zero)

[Sibghat]

So the xRange_new will read the indexes from x_index and pick the corresponding value from fnew (for valid indexes only).

Like if the value of index 1001 in x_index is 1, so the xRange_new = fnew(x_index) will display the value at position 1001 in the fnew array, right?

That's all...

Thank you. I understand it now.

BR.

[Mathieu NOE]

yes , you got it !

all the best

MN