Hello R-list,
How can I row wise solve a function for which the input variables are written
in a matrix or a vector and have the calculated output added to the matrix or
written in a vector?
To specify my case in particular I continue: I would like R to calculate for me
a value for t which is function of input parameters A and B, which are
comprised in a matrix called ddt and some other constants. q,p,u,v in this
example.
The equation (q*(1-exp(u*B*t))+( p*(1-exp(v*B*t)-A)
A and B may sometimes be missing values (NA (not a number)) because there
isnt always a result for each time step.
The matrix ddt looks like this
Datetime B A t
[772,] 12/12/2005 15:27:12 NA NA NA
[773,] 12/12/2005 16:27:12 5000000 1.24480000 NA
[774,] 12/12/2005 17:27:12 NA NA NA
[775,] 13/12/2005 13:27:12 7012500 2.64038000 NA
[776,] 13/12/2005 14:27:12 NA NA NA
[777,] 13/12/2005 15:31:28 NA NA NA
Ive tried to calculate t as followed
Af<-function(i,t){ (q*(1-exp(u*ddt[i,2]*t))+( p*(1-exp(v*ddt[i,2]*t)- ddt[i,3])
Because input B is listed in the second column and input A is listed in the
third column of the matrix ddt. The fourth column in ddt is meant for the row
wise output values of t.
To calculate t I've tried
output<-function(i){uniroot(Af,c(0,9999),i=i)}
Uniroot has been used on single input values for A and B and gives good results
and I would like to automate this. Therefore I tried to use mapply
t<-mapply(output,i=i)
This seems not work and therefore Im asking the list: how can I calculate in
R the row wise value for t?
Do you have a quick solution for it?
Kind regards,
Gunter Eerdekens
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