How can i define a parameter with if condition?

Question

Rajith 2013-2-4

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I want to define variables with if and switch conditions in simbiology. Is it possible to define using matlab code?

For example I have variable say

x = normrnd(140,104)
if x>440
  y = 440;
elseif x<40
  y = 40;
else
  x=y;
end

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Answer 1

Azzi Abdelmalek 2013-2-4

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编辑：Azzi Abdelmalek 2013-2-4

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You have to initialize y

y=0 %for example

%or maybe in the last else you wanted

y=x

then

x = normrnd(140,104)
y=x
if x>440
 y = 440;
elseif x<40
 y = 40;
end

%or without a for loop

x = normrnd(140,104)
y=40*(x<40)+440*(x>440)+x*(40<=x & x<=440)

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Answer 2

Arthur Goldsipe 2013-2-4

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Hi,

The short answer is that SimBiology cannot directly use "if" or "switch", but you can use them indirectly by putting them in a helper function. For example, to use the sample code you provided, create a file named "myrand.m" with the following content:

function y = myrand
x = normrnd(140,104)
if x>440
  y = 440;
elseif x<40
  y = 40;
else
  y = x; % I assume "x=y" was a typo
end

Then, to use this function to set the initial value of a species named "z" in a model stored in variable "m1", use the following command:

m1.addrule('z = myrand()', 'initialAssignment');

Further, as Azzi points out above, this particular example can be written without if or switch statements. Here's how I'd write the rule so that I didn't have to create a separate helper function:

m1.addrule('z = max(min(normrnd(140, 104), 440), 40)', 'initialAssignment');