# Getting the piecewise polynomial function of a 3D plot

3 ビュー (過去 30 日間)
Senal Perera 2021 年 3 月 16 日
コメント済み: Senal Perera 2021 年 3 月 16 日
Is there a method to get the piecewise function of the 3D plot below? My requirement is to get a value for X as the output when Y and Z are given as inputs. The plot is created using the curve fitting tool (linear interpolation)
Inputs should be - z , y
Output should be - x
##### 3 件のコメント1 件の古いコメントを表示1 件の古いコメントを非表示
ANKUR KUMAR 2021 年 3 月 16 日
Why are you using fitting tool GUI? You can do the same using interpolation code in a script.
DGM 2021 年 3 月 16 日
Unless I'm missing something, this is a more fundamental problem. If your goal is to get x from y and z, you need to note that your function is overdefined. In other words, there are multiple x values that may satisfy a given y,z pair. The conceptual consequences of that fact may vary depending on your usage.

サインインしてコメントする。

### 回答 (1 件)

ANKUR KUMAR 2021 年 3 月 16 日

You can use interp2 to calculate values programmatically.
clc
clear
[X,Y] = meshgrid(-5:1:5);
Z = Y.*sin(X) - 5*X.*cos(2*Y);
s = surf(X,Y,Z,'FaceAlpha',0.5);
[XX,YY] = meshgrid(-5:0.05:5);
ZZ=interp2(X,Y,Z,XX,YY);
figure
s = surf(XX,YY,ZZ,'FaceAlpha',0.5);
s.EdgeColor = 'none';
x_reqired=randi(50,1,10)/10;
y_reqired=randi(50,1,10)/10;
z_reqired=interp2(X,Y,Z,x_reqired,y_reqired)
##### 1 件のコメント-1 件の古いコメントを表示-1 件の古いコメントを非表示
Senal Perera 2021 年 3 月 16 日
I appreciate your effort Ankur. I guess interp2 is okay if z is needed as the output. But i need x as the output where z and y are inputs.

サインインしてコメントする。

### カテゴリ

Help Center および File ExchangeInterpolation についてさらに検索

R2019b

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by