Need To Find Value of Y at X for Curve Z. Detail Problem Explained in description

Hi all.

Ill just brief my problem.

in this work i have extracted data of X, Y for Particular Z curve : I have 26 Z curves in varying size of X & Y; :Code Attached

xx = [X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26]; % size (50 x 1)

yy = [Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 Y14 Y15 Y16 Y17 Y18 Y19 Y20 Y21 Y22 Y23 Y24 Y25 Y26]; % size (50 x 1)

zz = [5 6 7 8 9 10 12 14 16 18 20 25 30 35 40 50 60 70 80 90 100 120 150 200 250 300]; %for curve 5(X1,Y1) ... to 300 (X26,Y26)

in the above Code, X1 Y1 are same size(50X1) for Curve 5, (zz curve values are defined as 5, 6 and 10, 12 14 .. 150 200 250).

similarly for X2, Y2 for zz(2) =6;

similarly upto X26,Y26 for zz(26) = 300 ; (300 is curve value)

The plot looks like this below attached.

Question 1 : How to find Y value for 2 inputs of Z & X;

Input 1 : z = (between 200 and 150 - Say 165 I will give)

input 2 : xq value

Answer needed :

Output needed Yq = ????? How to get this.

Trying Grid data, Scattered data but my code is not working as zz value is not same size as X1 & Y1,

Please any help on this to get my result is really appricieted.

simply problem is if give any value of z and x i need y

Answer 1

[Chunru]

Without knowing your data, the following code only gives you an idea:

z0 = [5 6 7 8 9 10 12 14 16 18 20 25 30 35 40 50 60 70 80 90 100 120 150 200 250 300];
for i = 1:length(z0)
    xx{i, 1} = (0:.1:1)';   % the size can be varying with i
    yy{i, 1} = xx{i}.^2 * (1/(i+2));
    zz{i, 1} = z0(i) * ones(size(xx{i,1}));
end

% Assume your data is stored in the format avove

x = cell2mat(xx);
y = cell2mat(yy);
z = cell2mat(zz);
xq = 0.4; yq = 0.5;
whos

  Name        Size            Bytes  Class     Attributes

  i           1x1                 8  double              
  x         286x1              2288  double              
  xq          1x1                 8  double              
  xx         26x1              4992  cell                
  y         286x1              2288  double              
  yq          1x1                 8  double              
  yy         26x1              4992  cell                
  z         286x1              2288  double              
  z0          1x26              208  double              
  zz         26x1              4992  cell                

F = scatteredInterpolant(x,y,z);

Warning: Duplicate data points have been detected and removed - corresponding values have been averaged.

zq = F(xq, yq)

zq = 309.2008

[naveen kumar s]

Unable to perform assignment because brace indexing is not supported for variables of this type.

Error in TrailChecking (line 84)

xx{i, 1} = (0:0.1:1)'; % the size can be varying with i

my xx = [X1 ... Xn] is in matrix X1 has 50 rows 1 col. similarly for all X and Y.

.I am trying this method.

and I need to find Yq for (xq & Z curve)

[Chunru]

Is it possible for you to post your data?

To find yq:

F = scatteredInterpolant(x,z,y);
yq = F(xq, zq)

[naveen kumar s]

no, Data is Not sharable.

Data are like X1 Y1 for Z1 = 5 ; (X1,Y1 is in size of 50 x 1) but Z is scalar single value

checked with above code but still error it has:

Error using scatteredInterpolant

The input points must be specified in column-vector format.

Error in TrailChecking (line 68)

F = scatteredInterpolant(xx,zz,yy);

[Chunru]

Then use "whos" to show the relevant variable sizes.

[naveen kumar s]

Thank you @Chunru

Its Working well.

Answer 2

[KSSV]

Read about knnsearch, you provide (Y,Z) data and for a given (y,z) find which point is closest, get the index and assign the respective X value.

[naveen kumar s]

Ok, i will read on that.

Thank you.

Yes i should provide X, Z data to get X at nearest. How to do this is what i am searching