Keep y value below certain value in a loop

Question

Lukas Netzer 2021-4-17

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https://ww2.mathworks.cn/matlabcentral/answers/804956-keep-y-value-below-certain-value-in-a-loop

评论： Image Analyst 2021-4-19

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Hey,

I am trying to run a function, where y can never be below zero and never above Capacity.

The function looks like that:

remainingCharge = Capacity - usage + ChargingPower

So remainingCharge = y and is not allowed to go below 0 or beyond Capacity.

I've tried:

for x = 1:1:tablesize
t.remainingCharge = Capacity - t.usage(x) + t.ChargingPower(x)
if t.remainingCharge(x) > Capacity
remainingCharge(x) == Capacity
end
end

This is not working, as Capacity needs to be as long as the tablerows - currently I am adding Capacity to the table - hopfeully this works.

In the meantime if anyone has a suggestion on how to solve this I am happily taking hints!

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Answer 1

Image Analyst 2021-4-17

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https://ww2.mathworks.cn/matlabcentral/answers/804956-keep-y-value-below-certain-value-in-a-loop#answer_677616

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t.remainingCharge(x) = Capacity - t.usage(x) + t.ChargingPower(x) % x is the row number I think.
% Make it never be above Capacity
t.remainingCharge(x) = min([t.remainingCharge(x), Capacity]);
% Make it never be below 0
t.remainingCharge(x) = max([t.remainingCharge(x), 0]);

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Image Analyst 2021-4-19

Lukas, did min() and max() not work to clip the signal for some reason? Why not?

Also note I indexed t.remainingCharge so that you're not overwriting it each time.

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Answer 2

Star Strider 2021-4-17

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https://ww2.mathworks.cn/matlabcentral/answers/804956-keep-y-value-below-certain-value-in-a-loop#answer_677621

编辑：Star Strider 2021-4-17

在 MATLAB Online 中打开

Try something like this:

x = linspace(0, 5*pi, 250);
Capacity = 0.7;
limit_y = @(y,Capacity) (y<0).*0 + (y>Capacity).*Capacity + ((y>=0) & (y<Capacity)).*y;
y = sin(x);
figure
plot(x, y, 'LineWidth',1)
hold on
plot(x, limit_y(y,Capacity), '--', 'LineWidth',1.5)
hold off
grid
xlabel('x')
ylabel('y')
legend('Original','Limited', 'Location','best')

Note that no explicit loops are necessary, since the anonymous functrion does everything in one call.

The anonymous function is designed to work on vectors, however it is certainly possible to call the anonymous function in a loop with individual scalar values as the ‘y’ argument. It will work the same way, regardless.

Experiment with it to get the result you want.

EDIT — (17 Apr 2021 at 17:12)

Added plot image to illustrate function effect —

.

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Lukas Netzer 2021-4-18

在 MATLAB Online 中打开

My data looks like that:

pCp = potential Chargingpower --> describes what could possibly be charged

nCl = needed Chargingload --> describes what power is needed

rCl = remaining Chargingload --> describes remaining Capacity

So at line 1 my car arrives at destination, at line 2 it departs from that location and used 2.1499kW there but could have loaded 993.8750. Line 3 it arrives at the next location and used 343.98kW and could not charge. At line 4 it departs from that location, used 30.4566kW there but could have loaded 537.5... and so on. Now I need to calculate rCl for every step:

rCl

1000 --> start

656.02 --> drives and needs 343.98

1000 --> arrives, needs 30.4566, but can charge 343.98+30.4566

661.3947 --> drives and needs 336.0971

...

I tried doing that:

for x = 2:2:2734
Cp(x) = min((nC(x-1)+nC(x)),pCp(x))
end
for x = 2:1:2734
rC(x) = rC(x-1) - nC(x-1) + Cp(x-1)
end

but this actually will only charge a maximum of (nC(x-1)+nC(x)) and will eventually reduce the charged load as it is not charging to full when possible.

Sorry, but I just can't get my head around it..

Thanks for still reading ;)

Lukas Netzer 2021-4-19

Thanks for still hanging with me!

I am honestly struggling to explain it better, but will try again:

I have a car with an accumulator capacity of e.g. 1000kWh.

It starts with a full battery of 1000kWh in row 1 as it arrives at location 1.

In row 2 it is still at location 1 - needs 2.1499kWh but could potentially load the battery with 993.8750kWh (this obviously is not possible, as it can not charge over the 1000kWh capacity), therefor it loads 2.1499kWh at location 2.

In row 3 the remaining capacity is 1000kWh again (loaded to full in row 2) and it drives to location 2 and is using 343.98kWh - while on the road, it can not charge.

In row 4 it arrives at location 2 and has a remaining capacity of 656.02kWh (1000kWh-343.98kWh). At location 2 it needs 30.4566kWh but could potentially load 537.5kWh. As it cannot go over 1000kWh capacity it will load to 1000kWh again, as we have enough potential Chargingpower at this location.

In row 5 we yet again have a full battery and are on our way to location 3 and on our way there need 338.6053kWh and have no possibility to charge.

In row 6 we arrive at location 3 with a remaining load of 661.3947kWh. We will need 4.2998kWh at this location but could potentially charge 1.7*10^3 kWh. Yet again we have a surplus and we can charge to full.

And on it goes...

But somehow I can not figure out code that does that for me, as in row 16 we could potentially load to full again, but end up with 891kWh in row 17.

Is this explanation a little better this time?

Lukas Netzer 2021-4-19

在 MATLAB Online 中打开

I figured it out:

for x = 2:1:tablesize
rCl(x) = rCl(x-1)-nCl(x-1)+pCp(x-1)
if rCl(x) > 1000
rCl(x) = 1000
end 
end

Star Strider 2021-4-19

O.K.

I still do not completely understand it, however I am happy you got it to work.

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Keep y value below certain value in a loop

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Keep y value below certain value in a loop

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