"Missing" bar in Consumption screen

<div class='quotetop'>QUOTE(ScottR @ Aug 20 2006, 08:32 AM) [snapback]306244[/snapback]</div>

I get a "missing" bar when I haven't used any gas in a 5 minute period, like when parked on the freeway trying to get home from work.

 

There are a few other threads about this same issue, with some specualtion as to the logic behind this "feature". Take a look at this one.

 

I saw this yesterday for the first time. The blank space was during the time that I sat in line at the drive through at Starbucks.

 

<div class='quotetop'>QUOTE(ScottR @ Aug 20 2006, 12:02 PM) [snapback]306271[/snapback]</div>

I believe you. What sort of driving were you doing during that stretch?

I've gotten the zero bar a few times, under EITHER circumstance: using no gas/ICE while making it a short distance during the five minutes (thus the divide-by-zero bug described above), or using a smidgen of gas while traveling a very, very short distance during the five minutes (stuck in a jam, incredibly long traffic lights...). I'm not sure of the exact distance, but if it rounds down to zero miles, 0 MPG would be correct.

If I use no gas during a stretch in which I make it a significant distance, I get the joyful 99.9 mpg bar. But at low low miles, the calculations go wonky.

 

This is probably what it would look like if you do the BT mod and leave it off for a short period of time.

 

I get the "blank bar" syndrome when the car does not move for 5 minutes or only moves a little bit. This happens whether the ICE is running or not. If the car moves significantly during the 5 minute period with no ICE I get a full bar (99.0 MPG). I think that is the movement of the car that causes the display to register, not the condition of the ICE.

 

<div class='quotetop'>QUOTE(Snooze Button @ Aug 20 2006, 04:00 PM) [snapback]306382[/snapback]</div>

Yeah, that makes sense.

Scenario 1 - the ICE runs and the car doesn't move. That's 0 mpg.

Scenario 2 - the ICE runs and the car moves only a very small amount i.e., less than the distance it would take to acheive 1 mpg. That's still 0 mpg.

Scenario 3 - the ICE does not run and the car doesn't move. That's still 0 mpg.

Scenario 4 - the ICE doesn't run and the car does move. That's some miles per (divided by) zero gallons. Anything divided by zero is zero (division by zero error).

 

<div class='quotetop'>QUOTE(wilco @ Aug 20 2006, 07:44 PM) [snapback]306396[/snapback]</div>

I would guess the OP's situation was probably #3, since he does have two 99MPG bars closeby, it seems likely he was in heavy traffic, and for the missing bar he probably didn't move for 5 minutes. Just a guess...

In regions using L/100km (like Canada), it is not uncommon to get "missing bars" when in heavy traffic and able to last the entire 5 minutes in electric mode, regardless of distance travelled. B)

Kevin

 

<div class='quotetop'>QUOTE(Sarge @ Aug 20 2006, 05:22 PM) [snapback]306418[/snapback]</div>

Sure, because no liters burned is blank or zero. Blank bars are my goal

 

<div class='quotetop'>QUOTE(wilco @ Aug 20 2006, 05:44 PM) [snapback]306396[/snapback]</div>

I have to disagree here, both from mathematical and "real world" perspectives. First, anything divided by zero is not generally zero. A positive number (like miles driven) divided by zero (gallons of fuel used) is infinity. That is, you could drive infinite miles per gallon of gas consumed. Second, I live in the mountains and frequently drive for about 10 minutes with the ICE off going downhill. I cover about 7 miles during this period, and my consumption screen shows 99 MPG bars, not blanks, for these periods.

 

<div class='quotetop'>QUOTE(ScottR @ Aug 21 2006, 04:09 PM) [snapback]307091[/snapback]</div>

You can see this for yourself by simply leaving your car in the garage "ON" for 6 minutes, when you get back you will have a missing bar. I myself have gotten this when parked on the freeway or when going really slow for a 5 minute window or so.

 

<div class='quotetop'>QUOTE(climateguy @ Aug 21 2006, 03:45 PM) [snapback]307070[/snapback]</div>

Yeah, you're right about that, I made a mistake with scenario 4 (when applied to the US model Prius). What I meant was that if the ICE stays off and the car moves a very short distance (i.e. bumper to bumper crawling) you get a blank bar, but in retrospect, that might only occur when you travel less than one mile (which could be the zero error). With the metric models (like mine) you get blank bars if the ICE hasn't run regardless of distance travelled.

 

<div class='quotetop'>QUOTE(wilco @ Aug 21 2006, 09:08 PM) [snapback]307291[/snapback]</div>

By "metric models" do you mean those delivered to countries other than the U.S. or simply changing the display to metric readout? In other words, if I switch my display to km will I see blank bars or still the 99 MPG bars? (I'll try it out the next time I go "down the hill" but that probably won't be until the weekend.)

 

This is wrong. Anything divided by zero (including negative or zero) is _not defined_. That's not the same as infinity (according to my old A-level maths teacher anyway)

I get blank bars sometimes - once I got a blank bar with half a green car! The wife and I drove to go for a short walk, and parked in a very tight spot, and 30 mins or so later we returned. I must've spent a five minutes shuffling the car around to get it out of the space. The ICE didn't start, but I regenerated some charge, so I got half a car and no bar since I'd travelled a negligible difference.

 

<div class='quotetop'>QUOTE(molgrips @ Aug 22 2006, 08:36 AM) [snapback]307474[/snapback]</div>

Not to get too geeky (but hey, this is PriusChat! ) and hopefully not too off topic, but:

From a purely mathematical standpoint you are correct, x/0 is undefined for all x. However, in the real world example of MPG with zero gallons of fuel used, we can take the limit as fuel used approaches zero from the right to determine that MPG approaches (positive) infinity for any positive number of miles travelled. The mathematical argument against generally being able to do this is that one could also choose to take the limit as the denominator approaches zero from the left, which would then approach negative infinity for positive x, leading to a discontinuity and the reason x/0 is generally undefined. But unless your Prius is MAKING gasonline (in which case I want your car!), taking the limit from the left is nonsensical in this calculation, so only taking the limit from the right is justifiable, leading to an answer of infinity.

This also makes sense physically, since if you are not using any gas (the ICE is off), you could travel infinite miles for each gallon of gas in your tank (let's see how reliable the Prius REALLY is! )

 

<div class='quotetop'>QUOTE(climateguy @ Aug 21 2006, 09:30 PM) [snapback]307336[/snapback]</div>

I mean the former. There have been previous discussions where people were wondering whether the US Prius is "thinking" in US measurements, or whether it thinks in metric like the JDM, Euro, and Canadian models. The answer appeared to be that it was merely showing converted data. A case in point was that there are certain Fahrenheit temperatures that don't show on the US cars, eg. 76°F (which is between 24° and 25°C). The US MFD skips right from 75 to 77 (or so I've been told).

The Canadian cars show L/100KM on the MFD so when zero liters are burned for 5 minutes (regardless of distance traveled) a blank bar is shown. That's correct in the sense that no gas has been burned for 5 mins, but it obviously isn't the full story on fuel consumption because you're using captured energy from the previous bars. Anyway, along that line of thinking, if the US model converts the display to MPG, a zero liter consumption bar will convert to a zero MPG bar by way of a division by zero error. (the reason I used the Canadian model is that it's otherwise identical to the US model, made during the same production runs, and shipped on the same boats)

Keep in mind this is just 'net speculation. The Japanese domestic model reads in KM/L and does not show blank bars in the same situation (it shows full bars).

... and as for whether something divided by zero is zero or infinity... the Prius may be smart, but it skipped its advanced math classes to hang out with that flirty little Vitz.