Question

我想计算列表的总和，其中包含文本mpfr1的每个元素。

我有以下代码：

library(Rmpfr)
 ######  Central generalized Cofactorial   #####
 CgenC <- function(n,k,sigma){

  i <- 0:k
  B <- (-1)^i *choose(k,i)*pochMpfr((-i)*sigma, n)
  CgenC <- sum(B)*1/(factorial(k))
  return(CgenC)
  }

  #helpfunction
  hfun <- function(d,n,k,sigma,gamma){

   G <- choose(n,d)*CgenC(d,k,sigma)*pochMpfr(-(gamma), n-d)

  return(G)
  }

  NCgenC <- function(n,k,sigma,gamma){
   s <- k:n
  E <- sapply(s,hfun,n=n,k=k,sigma=sigma,gamma=gamma)

  NCgenC <- sum(E)
  return(NCgenC)
   }

可能还有比使用helpfunction更好的方法，但我是编程新手。

之后E看起来像：

[[1]]
'mpfr1' 58841424144769590802398501576045837205738093472425577422395207203116722951724046.536490917270720694092667549937401176716842829058677975377719677884520463728524151109618958095938032339354615748413119902638793141568563928308460798662023212923799608873996653084247997838235897625734493429191314427738979926169378387781579463813022200592226827918068083534511231048810054263460272712110560165030802860741581172618182744896043856500473312651443547811890843652043285582186302263502988917786388502716155013416710062301717698574066162109375

[[2]]
'mpfr1' 82871275202593779087122604776157996409481088998845801228666944089795992655102472.642373430793692374125929134125303485357643757531745742076715050078321471532137607446428722005372960997898005609266610074855955157895396722193218695989672456706464857213288691436880384233954098045336023019010212578667162712025383678754362300085837501918162183612037828788745867290227442574306429529728922577115900369140687795454923720717749187763638945864480587157831212835424687567575261647966653471636794832585905467382683540344896738333277759879099376438826851654084748588502407073974609375

...等

因此，R无法计算总和，因为它是一个列表，并且始终存在mpfr1。

我希望我已经清楚了。有人可以告诉我如何计算总和吗？

Answer 1

使用Rmpfr::mpfr2array函数将您的mpfr数字列表转换成mpfr数字数组，然后使用本机R sum函数。

library(Rmpfr)

vect = rep(0, 5)

for(i in 1:5){
  vect[i] = mpfr(x=10^-(10*i), precBits=100)
}
# My vector has just turned to a list
vect

# Sum of list is an error
sum(vect)


# Turn it to a vector 
converted_vect = Rmpfr::mpfr2array(vect, dim = length(vect))
converted_vect

# Now my sum and prod work fine and the precision is not lost
sum(converted_vect)
prod(converted_vect)

函数mpfr2array不应被用户调用，它也是包的内部函数。但是，这是我找到解决问题的方法。

r与Rmpfr包中的列表总和

1 个答案: