[R] Generate random vectors (continuous number) with a fixed sum

[Brian Smith]

Hi,

There is a function called RandVec in the package Surrogate which can
generate andom vectors (continuous number) with a fixed sum

The help page of this function states that:

a

The function RandVec generates an n by m matrix x. Each of the m
columns contain n random values lying in the interval [a,b]. The
argument a specifies the lower limit of the interval. Default 0.

b

The argument b specifies the upper limit of the interval. Default 1.

However in my case, the lower and upper limits are not same. For
example, if I need to draw a pair of number x, y, such that x + y = 1,
then the lower and upper limits are different.

I tried with below code

library(Surrogate)

RandVec(a=c(0.1, 0.2), b=c(0.2, 0.8), s=1, n=2, m=5)$RandVecOutput

This generates error with message

Error in if (b - a == 0) { : the condition has length > 1

Is there any way to generate the numbers with different lower and upper limits?