GURPS Space GURPS Math

[Langy]

Originally Posted by RyanW

Vehicles from 3e used cube roots as its most complicated math. Space has, if I remember right, square roots and fourth powers. I'd be surprised if any math in Vehicles Design is above that.

I wouldn't, really; we've been told that VDS will have more complex math than Vehicles 2e, if I remember right.

But VDS isn't going to be 'required' for GURPS and there'll almost certainly be automatic calculators for whatever pops up anyways, so people still won't need to understand the inner workings to use it.

[Langy]

Originally Posted by whswhs

I'm afraid I'm somewhere at the other end of the spectrum; for example, when I used Vehicles I would get out my calculator and find the exact cube roots instead of using the table, because it was faster and easier. Then there was the time when I'd mislaid my calculator and got out one of my slide rules (I keep two as ceremonial heirlooms) to approximate the cube roots. . . .

When I was working on Weird War II, though, I put in a table of multiples of exhaust velocity you could get as final velocity based on percentage of mass that was fuel/reaction mass, to spare people taking logarithms. If Spaceships has done the same thing I think that's a good idea.

Spaceships doesn't even get into that much detail - it doesn't even mention exhaust velocity in the actual books, only the designer's notes. It's a very abstracted system from the point of view of the designer, though the exhaust velocity calculations are used 'in the background' by the author to come up with the delta-V figures in the book and the actual equations used are exposed in the designer's notes article.

[Warden]

Here are some examples of the math I was speaking about in my first post

If local gravity is more than 1G, multiply the sum of your body weight and the weight of everything you’re carrying by (local gravity in Gs)-1.

In higher or lower gravity than usual, count the number of G-Increments from your home gravity, rounding down. This determines the penalties you suffer.

Page 431 "Alternatively, calculate velocity in yards per second as the square root of (21.4 x g x distance fallen in yards), where g is the local gravity in Gs (g = 1 on Earth). Round to the nearest whole number."

Page 431 The terminal velocity rules assume Earth-normal gravity (1G) and atmospheric pressure (1 atm.).

Multiply terminal velocity by the square root of gravity in Gs. Then divide it by the square root of pressure in atm.

Granted I know them now because of the generous help I've received from posters on these forums, and the second one is very easy once it clicked. But at first glance my eyes crossed when I saw talk of square roots, and stuff

[Langy]

Originally Posted by Warden

Here are some examples of the math I was speaking about in my first post

If local gravity is more than 1G, multiply the sum of your body weight and the weight of everything you’re carrying by (local gravity in Gs)-1.

In higher or lower gravity than usual, count the number of G-Increments from your home gravity, rounding down. This determines the penalties you suffer.

Page 431 "Alternatively, calculate velocity in yards per second as the square root of (21.4 x g x distance fallen in yards), where g is the local gravity in Gs (g = 1 on Earth). Round to the nearest whole number."

Page 431 The terminal velocity rules assume Earth-normal gravity (1G) and atmospheric pressure (1 atm.).

Multiply terminal velocity by the square root of gravity in Gs. Then divide it by the square root of pressure in atm.

Granted I know them now because of the generous help I've received from posters on these forums, and the second one is very easy once it clicked. But at first glance my eyes crossed when I saw talk of square roots, and stuff

All the square root stuff is optional - hence the 'alternatively' at the Page 431 remark.

If you have difficulty with that kind of math, simply don't use those rules. They're optional for a reason.

[Fred Brackin]

Originally Posted by RyanW

Vehicles from 3e used cube roots as its most complicated math. .

....but only twice and both times were in the Water Vehicles Performance formulas. There were workarounds offered too.

Ve2 might be more fairly characterized as having a high level of detail. This is a highly desirable feature for persons looking for detail. when I'm designing an important vehicle for PCs I want more detail than other design sequences will supply.

By contrast, Spaceships has a very low level of detail which leads to a fast, easy design sequence. A highly desirable feature for other people or even just the same people looking for a system to use for different purposes such as for fleets to be used by NPCs..

[whswhs]

Originally Posted by Fred Brackin

By contrast, Spaceships has a very low level of detail which leads to a fast, easy design sequence. A highly desirable feature for other people or even just the same people looking for a system to use for different purposes such as for fleets to be used by NPCs..

You know, this is kind of weird, I admit, but I've never been able to make any sense of the Spaceships design rules. I just look at them and I can't imagine how to do anything with them. I had to struggle with the Vehicles system, and there are things in it I find problematic, but it made sense to me in a way that Spaceships doesn't.

[Ulzgoroth]

Originally Posted by Warden

But at first glance my eyes crossed when I saw talk of square roots, and stuff

Frankly, the main thing that would be useful is to beat that reaction. Even if you really can't think about square roots (which, frankly, I have trouble believing), you don't need to. Firstly, in most cases (including that one) you can simply avoid the square root all together. Secondly, you don't need to think about the square root to use the formula, you just need to enter it into your calculator (my calculator is google, most of the time). Which is exactly what almost anyone else would do.

The fear of math is more a threat than the math itself.

Originally Posted by whswhs

You know, this is kind of weird, I admit, but I've never been able to make any sense of the Spaceships design rules. I just look at them and I can't imagine how to do anything with them. I had to struggle with the Vehicles system, and there are things in it I find problematic, but it made sense to me in a way that Spaceships doesn't.

I have a lot of issues with Spaceships, but I never had trouble seeing how it worked. I'm sure there's a number of us who'd be happy to try to help work it out if you want to.

[RyanW]

Originally Posted by Warden

Granted I know them now because of the generous help I've received from posters on these forums, and the second one is very easy once it clicked. But at first glance my eyes crossed when I saw talk of square roots, and stuff

The arithmetic in all those examples is pretty basic stuff. If you took math in high school, you were almost certainly exposed to it. Not if you took a focus on math, but if you had any high school level math at all. It's actually pretty trivial with even a basic pocket calculator.

What I suspect is the case is that you glass over when you have to turn words into arithmetic. There are plenty of people who have no problem with "4X+7=19" but if asked "If a group wants to split six twenty ounce water bottles evenly between eight people, how many ounces should each person get?" they would enter 'math is hard' mode. They see math as a series of steps to follow to get the answer the teacher wants, and never learned to apply any of it to actual situations. I largely blame the school system, which doesn't really care what happens to students after they finish taking the test.

[whswhs]

Originally Posted by Ulzgoroth

I have a lot of issues with Spaceships, but I never had trouble seeing how it worked. I'm sure there's a number of us who'd be happy to try to help work it out if you want to.

What I think might help is a simple step by step "This is how I design this particular simple spacecraft," with page references. I have no idea where anything is in the book, or how to find it, or what order I'm supposed to find it in.

[David Johnston2]

Originally Posted by RyanW

Vehicles from 3e used cube roots as its most complicated math. .

Every time people use that response they are failing to grasp the issue which is not that anyone is claiming that the math is truly difficult, but that it is laborious. It is not a matter of the quality of the mathematical operations, but their quantity.