Basic Calculation using R

常数

pi

## [1] 3.141593

exp(1)

## [1] 2.718282

简单运算

x = 2.1
y = -3.3
abs(y)

## [1] 3.3

x + y

## [1] -1.2

x - y

## [1] 5.4

x * y

## [1] -6.93

x / y

## [1] -0.6363636

x ** 2

## [1] 4.41

x ** (1/2)

## [1] 1.449138

ceiling(x)

## [1] 3

floor(x)

## [1] 2

ceiling(y)

## [1] -3

floor(y)

## [1] -4

三角函数

sin(pi)

## [1] 1.224647e-16

cos(pi)

## [1] -1

tan(pi)

## [1] -1.224647e-16

sin(pi/2)

## [1] 1

cos(pi/2)

## [1] 6.123234e-17

tan(pi/2)

## [1] 1.633124e+16

par(mfrow=c(2,3))
curve(sin(x), xlim=c(-pi, pi))
curve(cos(x), xlim=c(-pi, pi))
curve(tan(x), xlim=c(-pi/2, pi/2), ylim=c(-10,10))

curve(asin(x), xlim=c(-0.99, 0.99))
curve(acos(x), xlim=c(-0.99, 0.99))
curve(atan(x), xlim=c(-10,10))

指数运算

exp(1)

## [1] 2.718282

exp(2)

## [1] 7.389056

2**3

## [1] 8

2**0.5

## [1] 1.414214

2**-0.5

## [1] 0.7071068

对数运算

log(exp(2))     #以自然常数e为底

## [1] 2

log2(2**3)      #以2为底

## [1] 3

log10(10**4)    #以10为底

## [1] 4

微积分

D(expression(x**2 + 2*x +4), 'x')

## 2 * x + 2

D(expression(e**x), 'x')

## e^x * log(e)

D(expression(2**x), 'x')

## 2^x * log(2)

D(expression(10**x), 'x')

## 10^x * log(10)

D(expression(log(x)), 'x')

## 1/x

D(expression(log2(x)), 'x')

## 1/(x * log(2))

D(expression(log10(x)), 'x')

## 1/(x * log(10))

D(expression(sin(x)), 'x')

## cos(x)

D(expression(cos(x)), 'x')

## -sin(x)

D(expression(tan(x)), 'x')

## 1/cos(x)^2

D(expression(asin(x)), 'x')

## 1/sqrt(1 - x^2)

D(expression(acos(x)), 'x')

## -(1/sqrt(1 - x^2))

D(expression(atan(x)), 'x')

## 1/(1 + x^2)

D(expression(sin(x) + cos(x)), 'x')

## cos(x) - sin(x)

D(expression(sin(x) * cos(x)), 'x')

## cos(x) * cos(x) - sin(x) * sin(x)