Filtering through multiple vectors for a single set of values

I get the roots below using an equation solver & filtering out "unrealistic" roots with conditional/logical statements.

The part I'm stuck on is on how to code this proccess:

1) Identify the common integer at the beginning of the vector sets between Q1 - Q6 (in this case, 3)

2) Filter out the other vector sets (2,4)

3) Pull out the long decimal number from the #3 vector sets & assign that as the new Q1 Q2 etc

Q1 =
[ 2, 1, 1, 0.058437210716851634542028894189494]
[ 3, 1, 1, 0.058688566689220710419984397081727]
 
Q2 =
[ 2, 1, 1, 0.0098069127074167821263054682858129]
[ 3, 1, 1, 0.0078508603596354954926620927235173]
 
Q3 =
[ 2, 1, 1, 0.0015627892831483654579711058105059]
[ 3, 1, 1, 0.0013114333107792895800156029182727]
 
Q4 =
[ 2, 1, 1, 0.041562789283148365457971105810506]
[ 3, 1, 1, 0.041311433310779289580015602918273]
 
Q5 =
[ 3, 1, 1,  0.00083770632958521492732230435821]
[ 4, 1, 1, 0.020473081482478049769416844651268]
 
Q6 =
[ 3, 1, 1,  0.01083770632958521492732230435821]
[ 4, 1, 1, 0.030473081482478049769416844651268]

[Jacob Wood]

Will there always be a single integer that appears once in every Q_i?

[Chad Williams]

Yes it's purposely put there so the vector can be identified & only exists to point to the root. It will always be 1,2,3 & 4 for this application.

Below is the orginal output where you can see what would be 1 & 4 being filtered out as they are negative.

I just get stuck on trying to translate into code.

Q1 =
 -0.15604402697446315680842658977416
 0.058437210716851634542028894189494
 0.058688566689220710419984397081727
 -0.05986135947318542852737264354485
 
 Q1 =
 
[ 2, 0.058437210716851634542028894189494]
[ 3, 0.058688566689220710419984397081727]

Answer 1

[KSSV]

1) Identify the common integer at the beginning of the vector sets between Q1 - Q6 (in this case, 3)

Read about unique for this.

2) Filter out the other vector sets (2,4)

Use ismember for this.

3) Pull out the long decimal number from the #3 vector sets & assign that as the new Q1 Q2 etc

You can use logical indexing for this.

Answer 2

[Jacob Wood]

Chad,

This might be a solution for you. It picks the most common root label and grabs all of them:

Q1 = [ 2, 1, 1, 0.058437210716851634542028894189494;
       3, 1, 1, 0.058688566689220710419984397081727];
 
Q2 = [ 2, 1, 1, 0.0098069127074167821263054682858129;
       3, 1, 1, 0.0078508603596354954926620927235173];
 
Q3 = [ 2, 1, 1, 0.0015627892831483654579711058105059;
       3, 1, 1, 0.0013114333107792895800156029182727];
 
Q4 = [ 2, 1, 1, 0.041562789283148365457971105810506;
       3, 1, 1, 0.041311433310779289580015602918273];
 
Q5 = [ 3, 1, 1,  0.00083770632958521492732230435821;
       4, 1, 1, 0.020473081482478049769416844651268];
 
Q6 = [ 3, 1, 1,  0.01083770632958521492732230435821;
       4, 1, 1, 0.030473081482478049769416844651268];

Q = [Q1;Q2;Q3;Q4;Q5;Q6];

select_int = mode(Q(:,1));

roots = Q(Q(:,1)==select_int,4);

[Chad Williams]

That code works perfectly, however there is a formatting issue with implementing it into my main line of code. The formatting of my Q sets is different I'm assuming either to my preceeding code or the fact that it's symbolic before the calculations.

idx1 = find(Q1 < 0.1 & Q1 > 0);
[i1] = ind2sub(size(Q1), idx1);

Q1 = [i1 Q1(idx1)] %this is where I assume the issue is

Q1 = %output
 
[ 2, 0.058437210716851634542028894189494]
[ 3, 0.058688566689220710419984397081727]

[Jacob Wood]

I'm not sure I'm following. What is happening in these lines? Is this output from running the code?

[ 2, 0.058437210716851634542028894189494]
[ 3, 0.058688566689220710419984397081727]

[Chad Williams]

Yes those are the outputs.