[R] Solving a simple linear equation using uniroot give error object 'x' not found

[Jeff Newmiller]

Have you looked at the examples in ?uniroot? Don't call yfun... let uniroot do that.

On October 6, 2020 8:00:59 AM PDT, "Sorkin, John" <jsorkin using som.umaryland.edu> wrote:
>Colleagues,
>I am trying to learn to use uniroot to solve a simple linear equation.
>I define the function, prove the function and a call to the function
>works. When I try to use uniroot to solve the equation I get an error
>message,
>Error in yfu n(x,10,20) : object 'x' not found.
>
>I hope someone can tell we how I can fix the problem
>
>  if(!require(rootSolve)){install.packages("rootSolve")}
>  library(rootSolve)
>
>  # Define the function
>  yfun <- function(x,diffMean,diffSE) ((abs(diffMean)-x)/diffSE)
>  # Prove the function and a call to the function work
>  yfun(10,100,10)
>  # use uniroot to find a solution to the
>  # function in the range -100 to 100
>  uniroot(yfun(x,10,20),c(-100,100))
>
>
>My output:
>>   # Define the function
>>   yfun <- function(x,diffMean,diffSE) ((abs(diffMean)-x)/diffSE)
>>   # Prove the function and a call to the funciton works
>>   yfun(10,100,10)
>[1] 9
>>   # use uniroot to find a solution to the
>>   # funciton in the range -100 to 100
>>   uniroot(yfun(x,10,20),c(-100,100))
>Error in yfun(x, 10, 20) : object 'x' not found
>
>Thank you,
>John
>
>
>John David Sorkin M.D., Ph.D.
>Professor of Medicine
>Chief, Biostatistics and Informatics
>University of Maryland School of Medicine Division of Gerontology and
>Geriatric Medicine
>Baltimore VA Medical Center
>10 North Greene Street
>GRECC (BT/18/GR)
>Baltimore, MD 21201-1524
>(Phone) 410-605-7119
>(Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
>
>	[[alternative HTML version deleted]]
>
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-- 
Sent from my phone. Please excuse my brevity.