bad argument #1 to 'random' (interval is empty)?!?!?

[TheBreadCat]

im making a 1d terrain genarator.
but there is a problem:

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hm = {}--height map
hp = {}--height points
lp = {}--low points
mf = 2--mutate factor

function init()
	math.randomseed( os.time() )
	for i = 0 , 9 do
		hm[i] = {}
	end
	for i = 0 , 9 do
		hm[i] = math.random(0,9)
	end
end
init()

for i = 0 , 9 do
	pon = math.random(0,1)
	if i == 0 then
		io.write(math.random(math.floor((0 - hm[i+1])/2)))
	elseif i == 9 then
		io.write(math.random(math.floor((hm[i-1] - 0)/2)))
	else
		io.write(math.random(math.floor((hm[i-1] - hm[i+1])/2)).." ")
	end
	io.write(hm[i].." ")
end

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lua: c.lua:20: bad argument #1 to 'random' (interval is empty)

[Robin]

The problem is probably in one of the lines:

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io.write(math.random(math.floor((0 - hm[i+1])/2)))
io.write(math.random(math.floor((hm[i-1] - 0)/2)))
io.write(math.random(math.floor((hm[i-1] - hm[i+1])/2)).." ")

When calling math.random with a single argument, make sure that argument is > 0. Perhaps doing something like

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io.write(math.random(math.floor((0 - hm[i+1])/2)+1))
io.write(math.random(math.floor((hm[i-1] - 0)/2)+1))
io.write(math.random(math.floor((hm[i-1] - hm[i+1])/2+1)).." ")

Although I don't really understand the purpose of this code.

[Taehl]

Apparently the math in your call to math.random on line 20 is resulting in a number that's less than one. Make sure it's greater than or equal to 1.

[TheBreadCat]

Apparently the math in your call to math.random on line 20 is resulting in a number that's less than one. Make sure it's greater than or equal to 1.

but i need a negative value.
so do i have to make a if statement to check if the value is negative , and if so then set it to the minimum of the random function?
like this:

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for i = 0 , 9 do
	pon = math.random(0,1)
	if i == 0 then
		if math.floor((0 - hm[i+1])/2) < 0 then
			io.write(math.random(math.floor((0 - hm[i+1])/2)),0)
		else
			io.write(math.random(math.floor((0 - hm[i+1])/2)))
		end
	elseif i == 9 then
		if math.floor((0 - hm[i+1])/2) < 0 then
			io.write(math.random(math.floor((0 - hm[i-1])/2)),0)
		else
			io.write(math.random(math.floor((0 - hm[i-1])/2)))
		end
	else
	if math.floor((0 - hm[i+1])/2) < 0 then
			io.write(math.random(math.floor((hm[i-1] - hm[i+1])/2),0).." ")
		else
			io.write(math.random(math.floor((0 - hm[i+1])/2)))
		end
	end
	io.write(hm[i].." ")
end

[Robin]

I'm sorry, it's hard to help you if we can't tell what this code is supposed to do.

[BlackBulletIV]

A solution that will work is to use the opposite positive number for math.random and then negate the result to get it back to negative. If you need to get a negative number to positive you can use the negation operator, and the same for getting it back to negative. For example:

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io.write(-math.random(-math.floor((hm[i-1] - hm[i+1])/2)).." ")

[Robin]

A solution that will work is to use the opposite positive number for math.random and then negate the result to get it back to negative. If you need to get a negative number to positive you can use the negation operator, and the same for getting it back to negative. For example:

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io.write(-math.random(-math.floor((hm[i-1] - hm[i+1])/2)).." ")

I'm not sure if what you are doing is what the OP wants, but if so: I think this also works:

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io.write(math.random(math.floor((hm[i-1] - hm[i+1])/2), 0).." ")

[kikito]

but i need a negative value.

This might sound a bit obvious, but there it goes - if you multiply any positive value with -1 you get a negative value.

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my_negative_value = my_positive_value * -1

As others are saying, knowing the context of your problem will probably help us help you better.

[BlackBulletIV]

A solution that will work is to use the opposite positive number for math.random and then negate the result to get it back to negative. If you need to get a negative number to positive you can use the negation operator, and the same for getting it back to negative. For example:

Code: Select all

io.write(-math.random(-math.floor((hm[i-1] - hm[i+1])/2)).." ")

I'm not sure if what you are doing is what the OP wants, but if so: I think this also works:

Code: Select all

io.write(math.random(math.floor((hm[i-1] - hm[i+1])/2), 0).." ")

Negating a number twice will you the same number. But if that works that's cool.

but i need a negative value.

This might sound a bit obvious, but there it goes - if you multiply any positive value with -1 you get a negative value.

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my_negative_value = my_positive_value * -1

As others are saying, knowing the context of your problem will probably help us help you better.

Or you could use the negation operator (-):

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my_negative_value = -my_positive_value

[miko]

Apparently the math in your call to math.random on line 20 is resulting in a number that's less than one. Make sure it's greater than or equal to 1.

but i need a negative value.

But math.random() needs a positive value.
If you want to get a random number between -10 and 10 do something like this:

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value=math.random(0,20)-10