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function handle in a loop

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Sarah Kern
Sarah Kern on 22 Jan 2020 at 17:38
Commented: Walter Roberson on 23 Jan 2020 at 8:58
Hello,
I have the following objective function in my optimization matlab function block
if f_lag > 0 % decision braking or driving mode
fun =@(x) (A/SOC_1)*(b(1))^2+(A/SOC_2)*(x(2))^2+(A/SOC_3)*(x(3))^2+(A/SOC_4)*(x(4))^2+d_delay_1-(SW_1+x(5))+d_delay_2-(SW_2+x(6))+d_delay_3-(SW_3+x(7))+d_delay_4-(SW_4+x(8));
else
fun =@(x) ((B*M_reg_1)/SOC_1)*(1/(x(1))^2)+((B*M_reg_2)/SOC_2)*(1/(x(2))^2)+((B*M_reg_3)/SOC_3)*(1/(x(3))^2)+((B*M_reg_4)/SOC_4)*(1/(x(4))^2)+d_delay_1-(SW_1+x(5))+d_delay_2-(SW_2+x(6))+d_delay_3-(SW_3+x(7))+d_delay_4-(SW_4+x(8));
end
but because of code generation simulink/matlab, doesnt allow the function handles in the if loop.
Can someone help me what to do?
would be very glad, thank you!

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Accepted Answer

Walter Roberson
Walter Roberson on 22 Jan 2020 at 20:57
Provided that the two calculations return the same size of values, and provided that neither calculation ever returns inf or nan, then the general form
if condition
f = @(x) expression1
else
f = @(x) expression2
end
Can be rewritten as
f = @(x) (condition).*expression1 +
(~condition).*expression2
This is seldom the most efficient approach. Typically it would be more efficient to create both function handles and later test which one should be used.

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Sarah Kern
Sarah Kern on 23 Jan 2020 at 8:33
Thank you very much, so like this?
f =@(x) (f_lag == 1).*(A/SOC_1)*(x(1))^2+(A/SOC_2)*(x(2))^2+(A/SOC_3)*(x(3))^2+(A/SOC_4)*(x(4))^2+d_delay_1-(SW_1+x(5))+d_delay_2-(SW_2+x(6))+d_delay_3-(SW_3+x(7))+d_delay_4-(SW_4+x(8));
+ (f_lag == -1).*((B*M_reg_1)/SOC_1)*(1/(x(1))^2)+((B*M_reg_2)/SOC_2)*(1/(x(2))^2)+((B*M_reg_3)/SOC_3)*(1/(x(3))^2)+((B*M_reg_4)/SOC_4)*(1/(x(4))^2)+d_delay_1-(SW_1+x(5))+d_delay_2-(SW_2+x(6))+d_delay_3-(SW_3+x(7))+d_delay_4-(SW_4+x(8));
It wont let me create both function handles, that's what I tried before.
Walter Roberson
Walter Roberson on 23 Jan 2020 at 8:58
That code looks plausible.
It will let you create both function handles: just store them in different variables and invoke the appropriate one. You might even be able to store them in a cell array and index that at (f_lag+3)/2

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More Answers (1)

Sarah Kern
Sarah Kern on 23 Jan 2020 at 8:32
Thank you very much, so like this?
f =@(x) (f_lag == 1).*(A/SOC_1)*(x(1))^2+(A/SOC_2)*(x(2))^2+(A/SOC_3)*(x(3))^2+(A/SOC_4)*(x(4))^2+d_delay_1-(SW_1+x(5))+d_delay_2-(SW_2+x(6))+d_delay_3-(SW_3+x(7))+d_delay_4-(SW_4+x(8));
+ (f_lag == -1).*((B*M_reg_1)/SOC_1)*(1/(x(1))^2)+((B*M_reg_2)/SOC_2)*(1/(x(2))^2)+((B*M_reg_3)/SOC_3)*(1/(x(3))^2)+((B*M_reg_4)/SOC_4)*(1/(x(4))^2)+d_delay_1-(SW_1+x(5))+d_delay_2-(SW_2+x(6))+d_delay_3-(SW_3+x(7))+d_delay_4-(SW_4+x(8));
It wont let me create both function handles, that's what I tried before.

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