CODEWITHSUNDEEP
rfunctionmathvector
badger204
badger204

Reputation: 47

Writing Quadratic Function in R

I am a beginner using R, and I am trying to write a simple quadratic function in R that accepts values for a, b, c and x and returns a value for y: y = a + bx + cx^2, and from that, create and save a vector, x, of 101 equally spaced values from -2 to 2 inclusive. Using the vector x just constructed, and the following values a = -1, b = 0, c = 1 with your function, calculate and save values for a vector, y.

My code so far is below:

MyFunction <- function(x){y = a + bx + cx^2^
}
x <- seq(from = -2, to = 2, length.out = 101)
print(x)
a=-1
b=0
c=1

As you can see I have some of the basics down, but am having trouble put the pieces together. Any help is greatly appreciated! Thanks in advance.

Upvotes: 2

Views: 11785

Answers (2)

Italo Cegatta
Italo Cegatta

Reputation: 430

Putting all answer together from @m-dz and @eipi10, we have:

MyFunction <- function(x, a=-1, b=0, c=1){
  a + b*x + c*x^2 
}

x <- seq(from = -2, to = 2, length.out = 101)

result <- MyFunction(x)

> result
  [1]  3.0000  2.8416  2.6864  2.5344  2.3856  2.2400  2.0976  1.9584  1.8224  1.6896  1.5600  1.4336  1.3104  1.1904  1.0736
 [16]  0.9600  0.8496  0.7424  0.6384  0.5376  0.4400  0.3456  0.2544  0.1664  0.0816  0.0000 -0.0784 -0.1536 -0.2256 -0.2944
 [31] -0.3600 -0.4224 -0.4816 -0.5376 -0.5904 -0.6400 -0.6864 -0.7296 -0.7696 -0.8064 -0.8400 -0.8704 -0.8976 -0.9216 -0.9424
 [46] -0.9600 -0.9744 -0.9856 -0.9936 -0.9984 -1.0000 -0.9984 -0.9936 -0.9856 -0.9744 -0.9600 -0.9424 -0.9216 -0.8976 -0.8704
 [61] -0.8400 -0.8064 -0.7696 -0.7296 -0.6864 -0.6400 -0.5904 -0.5376 -0.4816 -0.4224 -0.3600 -0.2944 -0.2256 -0.1536 -0.0784
 [76]  0.0000  0.0816  0.1664  0.2544  0.3456  0.4400  0.5376  0.6384  0.7424  0.8496  0.9600  1.0736  1.1904  1.3104  1.4336
 [91]  1.5600  1.6896  1.8224  1.9584  2.0976  2.2400  2.3856  2.5344  2.6864  2.8416  3.0000

plot(result)

Plot

Upvotes: 4

Gustav Rasmussen
Gustav Rasmussen

Reputation: 3961

First off, there is an extra ^ operator at the end of the quadratic formula. See this link for defining and plotting a simple quadratic formula in r: http://rstudio-pubs-static.s3.amazonaws.com/275_8e3191f1f68f46229b30c361c6778dec.html

Upvotes: 0

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