How to have 'if statements' when defining 'constants'?

Question

A 2015-5-3

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/214869-how-to-have-if-statements-when-defining-constants

评论： Star Strider 2015-5-3

Hi guys,

I want to use 'if statements' to set certain constants in my surface. I have created this example of what I am trying to do. I want 'SomeConstant' to be a certain thing based on what the 'y' value is?

x = [0:100];
y = [0:100];
SomeConstant = 1;
if y <20
SomeConstant = 5;
else if y>20
SomeConstant = 10;
Test1 = @(x,y)(x+y)+SomeConstant;
Test2 = @(x,y)(x.^2+y)+SomeConstant;
[X1,Y1] = meshgrid(x,y);
Z1 = Test1(X1,Y1);
Z2 = Test2(X1,Y1);
s1 = surf(X1,Y1,Z1,'LineStyle','none');
hold on
s2 = surf(X1,Y1,Z2,'LineStyle','none');

Thank you

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Answer 1

Star Strider 2015-5-3

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/214869-how-to-have-if-statements-when-defining-constants#answer_177627

在 MATLAB Online 中打开

I would create ‘SomeConstant’ as an anonymous function:

x = [0:100];
y = [0:100];
SomeConstant = @(y) [1*(y == 20) + 5*(y < 20) + 10*(y > 20)];
Test1 = @(x,y)(x+y)+SomeConstant(y);
Test2 = @(x,y)(x.^2+y)+SomeConstant(y);
[X1,Y1] = meshgrid(x,y);
Z1 = Test1(X1,Y1);
Z2 = Test2(X1,Y1);
s1 = surf(X1,Y1,Z1,'LineStyle','none');
hold on
s2 = surf(X1,Y1,Z2,'LineStyle','none');

You defined ‘SomeConstant’ to be 1, and then defined it as being 5 for y<20 and 10 for y>20. I created the anonymous function version with those conditions, adding the condition that it was 1 at y==20.

This works, but you have to determine if it produces the result you want.