蠍一豺 z = (螳 - 蠏) / 譴ク谿
ク谿豺 t = 10z +50

-> ク谿豺襦 Slope襯 蟲れ

螳 = ATan(Slope) * 180/Pie;

x 蠍語願 36, y 蠍語願 3企朱
angle <- atan(3/36) * (180/pi)

--https://stackoverflow.com/questions/1897704/angle-between-two-vectors-in-r
覦燕
angle <- function(x,y){
  dot.prod <- x%*%y 
  norm.x <- norm(x,type="2")
  norm.y <- norm(y,type="2")
  theta <- acos(dot.prod / (norm.x * norm.y))
  as.numeric(theta)
}

x <- as.matrix(c(2,1))
y <- as.matrix(c(1,2))
angle(t(x),y)          # Use of transpose to make vectors (matrices) conformable.
[1] 0.6435011

slope to angle #

regression 蟆郁骸螳 企る..
    x <- (1:length(y)) * (max(y) - min(y)) / length(y)
    m <- lm(y~x)
    pred <- predict(m, newdata=data.frame(x,y), interval = "predict", level=.9)
    agl <- atan(coef(m)[2]) * (180/pi)


A <- c(1,2,3,4,5)
B <- c(6,7,8,9,10)
acos(sum(A*B) / (sqrt(sum(A^2)) * sqrt(sum(B^2)))) * (180/pi)