# Error: uq\_gradient (line 180) ExpDesign(ii).Y = fun(ExpDesign(ii).X);

**URL:** <https://uqworld.org/t/error-uq-gradient-line-180-expdesign-ii-y-fun-expdesign-ii-x/1723>\
**Category:** Community Q&A and How To\
**Tags:** metamodeling, reliability\
**Created:** [October 7, 2022, 7:30am UTC](https://uqworld.org/t/error-uq-gradient-line-180-expdesign-ii-y-fun-expdesign-ii-x/1723 "2022-10-07T07:30:12Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![koumm152](https://uqworld.org/letter_avatar_proxy/v4/letter/k/e36b37/32.png) [@koumm152](https://uqworld.org/u/koumm152)\
**Post date:** [October 7, 2022, 7:30am UTC](https://uqworld.org/t/error-uq-gradient-line-180-expdesign-ii-y-fun-expdesign-ii-x/1723/1 "2022-10-07T07:30:12Z")

</div>

```matlab
clc
clear all
format long
%% 
mu_x = [3 15 125 5 48 22];
sig_x = [0.00015 0.00075 0.000625 0.0025 0.24 0.0011];
rA =1.43e4;
h = 3.78;
ns = length(mu_x);
uqlab;
%% 
G = @(mu_x)rA-(mu_x(:,1).*mu_x(:,2).*mu_x(:,3).*mu_x(:,4).*(0.5.*(cos(mu_x(:,5).*pi./180)-cos(mu_x(:,6).*pi./180))));
n=100;
X1=lhsnorm(mu_x,diag(sig_x.^2),n);Y1=G(X1);
MetaOpts.Type='Metamodel';
MetaOpts.MetaType='SVR';
MetaOpts.ExpDesign.X=X1;
MetaOpts.ExpDesign.Y=Y1;
MetaOpts.Kernel.Family='Exponential';  
MetaOpts.QPSolver='SMO';
MetaOpts.Loss='l1-eps';
MetaOpts.EstimMethod='CV';
MetaOpts.Optim.Method='GA';
mySVR=uq_createModel(MetaOpts);
BHgx1 = uq_gradient(mu_x,mySVR);

```

```matlab
BHgx1 = uq_gradient(mu_x,mySVR);
The array index must be a positive integer or logical value
error uq_gradient (line 180)
                    ExpDesign(ii).Y = fun(ExpDesign(ii).X);

```

What should X be when you use uq\_gradient(X, fun, GradientMethod, FDStep, GivenH, KnownX, Marginals) to solve for a gradient？

---

<div class="post-metadata">

**Author:** ![styfen.schaer](https://uqworld.org/user_avatar/uqworld.org/styfen.schaer/32/849_2.png) [@styfen.schaer](https://uqworld.org/u/styfen.schaer)\
**Post date:** [October 7, 2022, 5:15pm UTC](https://uqworld.org/t/error-uq-gradient-line-180-expdesign-ii-y-fun-expdesign-ii-x/1723/2 "2022-10-07T17:15:10Z")

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Dear @koumm152

You need to wrap your SVR model in a function to make it work, e.g.:

```matlab
func = @(X) uq_evalModel(mySVR, X);
BHgx1 = uq_gradient(X1, func);

```

Best regards  
Styfen

---

<div class="post-metadata">

**Author:** ![koumm152](https://uqworld.org/letter_avatar_proxy/v4/letter/k/e36b37/32.png) [@koumm152](https://uqworld.org/u/koumm152)\
**Post date:** [October 8, 2022, 7:03am UTC](https://uqworld.org/t/error-uq-gradient-line-180-expdesign-ii-y-fun-expdesign-ii-x/1723/4 "2022-10-08T07:03:06Z")

</div>

Thank you for your reply. This problem has been solved perfectly with your help.

Best regard  
Maomao Kou