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[Solved] How to calculate "ppf"

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Posts: 15
 Sae
Topic starter
(@sae)
Active Member
Joined: 3 years ago

 

Hello dear..., all.

 

I have a basic question.

I can't understand how to calculate value of "ppf".

 

An age-dependent differential pathlength factor (DPF) was computed for each participant, I think.

I used default value of ppf "1", and it run without any problem.

Although I wonder if it's okay to keep the default.

 

Kind regards,

Sae 

 

4 Replies
Posts: 15
 Sae
Topic starter
(@sae)
Active Member
Joined: 3 years ago

As for above question,

I have understood by checking some articles etc... .

Thank you.

 

Sae

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Posts: 309
(@dboas)
Joined: 4 years ago

Excellent. For the benefit of others, can you paste the citation here of the article you read? Thanks

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Posts: 11
(@cpickouol)
Eminent Member
Joined: 1 year ago

Here is a Matlab code for working out DPF (which can be entered as a substitute for PPF in Homer3, due to a lack of PVF values)

 

The example here is for ages 18-30 and wavelengths 780nm and 850nm but you can play around with the parameters to suit your data

 

% Define the wavelength values
lambda1 = 780; % Wavelength in nm
lambda2 = 850; % Wavelength in nm

% Define the age range
ages = 18:30; % Ages from 18 to 30

% Initialize arrays to store DPF values for both wavelengths
DPF_780nm = zeros(size(ages));
DPF_850nm = zeros(size(ages));

% Parameters for the DPF calculation
a = 223.3;
b = 0.05624;
c = 0.8493;
d = -5.723E-7;
e = 0.001245;
f = -0.9025;

% Calculate DPF for each age at both wavelengths
for i = 1:length(ages)
    A = ages(i);
    DPF_780nm(i) = a + b * A^c + d * lambda1^3 + e * lambda1^2 + f * lambda1;
    DPF_850nm(i) = a + b * A^c + d * lambda2^3 + e * lambda2^2 + f * lambda2;
end

% Display the results
disp('Age    DPF (780nm)    DPF (850nm)');
disp([ages', DPF_780nm', DPF_850nm']);
Age    DPF (780nm)    DPF (850nm)
% Define the wavelength values
lambda1 = 780; % Wavelength in nm
lambda2 = 850; % Wavelength in nm

% Define the age range
ages = 18:30; % Ages from 18 to 30

% Initialize arrays to store DPF values for both wavelengths
DPF_780nm = zeros(size(ages));
DPF_850nm = zeros(size(ages));

% Parameters for the DPF calculation
a = 223.3;
b = 0.05624;
c = 0.8493;
d = -5.723E-7;
e = 0.001245;
f = -0.9025;

% Calculate DPF for each age at both wavelengths
for i = 1:length(ages)
    A = ages(i);
    DPF_780nm(i) = a + b * A^c + d * lambda1^3 + e * lambda1^2 + f * lambda1;
    DPF_850nm(i) = a + b * A^c + d * lambda2^3 + e * lambda2^2 + f * lambda2;
end

% Display the results
disp('Age    DPF (780nm)    DPF (850nm)');
disp([ages', DPF_780nm', DPF_850nm']);
Age    DPF (780nm)    DPF (850nm)
   18.0000    5.8768    4.8786
   19.0000    5.9075    4.9094
   20.0000    5.9381    4.9399
   21.0000    5.9683    4.9702
   22.0000    5.9984    5.0003
   23.0000    6.0283    5.0302
   24.0000    6.0580    5.0599
   25.0000    6.0875    5.0894
   26.0000    6.1168    5.1187
   27.0000    6.1460    5.1478
   28.0000    6.1749    5.1768
   29.0000    6.2038    5.2056
   30.0000    6.2325    5.2343
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Posts: 11
(@annalisa-palmisano)
Active Member
Joined: 4 months ago

Dear Christopher, 
Do you suggest inserting the DPF in Homer3? 
As I know ppf = 1/60 *DPF

Thank you,
Annalisa

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