Problems with defining a Conditional Formula - Max Y-axis value

Question

Mark Janssen 2020-12-18

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/697240-problems-with-defining-a-conditional-formula-max-y-axis-value

评论： Walter Roberson 2020-12-19

Hello,

I am looking for a way to solve a formula upto a certain y (P_Cathode) value, what would be the possible ways to go about this?

I was thinking doing using if, else statements but they do not seem to work. At this point I feel lost.

code:

t = [0:1:500]; 
if P_Cathode >= P_Max_Storage_Pa; 
    P_Cathode >= P_Max_Storage_Pa; %[Pa]
else
    P_Cathode = P_Start_Storage_Pa+((Molair_Mass_Flow_Hours*t)*R*T_Hydrogen_Cathode_K)/(V_storage_m3); %[Pa]
end

Here P_Max_Storage_Pa has a defined value.

Matlab states "Unrecognized function or variable 'P_Cathode'" and I don't know how to solve this, as this is a formula that is solved.

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Answer 1

Walter Roberson 2020-12-18

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/697240-problems-with-defining-a-conditional-formula-max-y-axis-value#answer_579085

在 MATLAB Online 中打开

P_Cathode = min(P_Max_Storage_Pa, P_Start_Storage_Pa+((Molair_Mass_Flow_Hours*t)*R*T_Hydrogen_Cathode_K)/(V_storage_m3) )

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Mark Janssen 2020-12-18

编辑：Mark Janssen 2020-12-18

Thanks a lot,

The correct values now appear in the command window, but the workspace still displays it wrongly, how would I get the correct values into the workspace, so I can plot them?

Walter Roberson 2020-12-19

That code is an asignment. If the output displayed from it does not match the values stored in the variables, there are a few possibilities:

you are using format short which is abbreviating the display in a way that is misleading you about what the values really are. Use format long g instead.
your preferences for looking at the workspace are using a format that is misleading you as to what the values really are. The workspace browser has a drop-down that allows you to select a different format, or you can set something in Preferences to give you a better format
or perhaps you are looking in the wrong workspace
or perhaps you did not arrange to return the P_Cathode calculated here into the right workspace