Index exceeds matrix dimensions : Error

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hydrogall
hydrogall 2016-2-4
评论： hydrogall 2016-2-5
I have a long for loop with many IF statements. I keep arriving at the error:
Index exceeds matrix dimensions.
Error in ESCIMOloop (line )
ShortRadBal(t)=(1 - Albedo(t))*GlobalRad(t);
Attempted to access Albedo(2); index out of bounds because numel(Albedo)=1.
Albedo is calculated earlier in the for-loop, so I don't understand why following equations are saying it is out of bounds. The Albedo at T(1)=0, but all following albedos should be calculated starting with line 79. I'm new to matlab and very confused.
%ESCIMO energy balance method for snow melting.
%Data from the ... Switzerland
clear all
x=load('C:\Users\wesser\Desktop\P2\ESCIMO\ESCIMOdata.dat'); %Load the file with data
%Field Observed Parameters
td=x(:,4); %hour of the day
T=x(:,5); %Air Temperature (K)
Relhum=x(:,6); %Relative Humidity (%)
Wind=x(:,7); %Wind Speed (m/s)
P=x(:,8); %Precipitation (mm/h)
GlobalRad=x(:,9); %Global Radiation (W/m2)
Inlong=x(:,10); %Incoming Longwave Radiation (W/m2)
Snow_obs=x(:,11); %SWE Observed
%List parameters that start with a known value at t=1
VapPresS(1)=0; %Surface Vapor Pressure is 0 a the start
Sublim(1)=0; %(Re-)Sublimation is 0 at the start
Melt(1)=0; %Melt is 0 at the start
ModeledSWE(1)=0; %Modeled SWE is 0 at the start
SnowAge(1)=0; %Snow age is 0 at the start
Albedo(1)=0; %Albedo is 0 at the start
%Parameters (to be CALIBRATED)
PM=importdata('C:\Users\wesser\Desktop\P2\ESCIMO\parameter.txt'); % model parameters input
Amin=PM(1,:); %Minimum Albedo
Aadd=PM(2,:); %Additive Albedo
DPp=PM(3,:); %Decline parameter (Positive temperatures)
DPn=PM(4,:); %Decline parameter (negative temperatures)
SS=PM(5,:); %Significant snowfall (mm/h)
Tp=PM(6,:); %Phase transition Temperature (K)
Se=PM(7,:); %Snow Emissivity
SHF=PM(8,:); %Soil Heat Flux (W/m2)
%Calibrated parameter ranges ------TBD
%Amin - # to # %Minimum Albedo
%Aadd - # to # %Additive Albedo
%DPp - # to # %Decline parameter (Positive temperatures)
%DPn - # to # %Decline parameter (negative temperatures)
%SS - # to # %Significant snowfall (mm/h)
%Tp - # to # %Phase transition Temperature (K)
%Se - # to # %Snow Emissivity
%SHF - # to # %Soil Heat Flux (W/m2)
%PARAMETERS (used default)
SHCW=4180.0; %Specific heat capacity of water (J/(kgK))
SHCS=2100.0; %Specific heat capacity of snow (J/(kgK))
MH=337500.0; %Melting heat (J/kg)
SBC=0.0000000567; %Stefan-Boltzmann-Constant (W/(m2K^4))
CSH=2835500.0; %Condensation/Sublimation heat (J/kg)
%Precipitation Loop
for t=2 : length(P); %time series loop
if T(t)>=Tp; %Precip that is rain
Pr(t)=P(t);
else
Pr(t)=0;
end
if T(t)<Tp; %Precip that is snow
Ps(t)=P(t);
else
Ps(t)=0;
end
if Ps(t)>SS; %Snow age
SnowAge(t)=0;
if ModeledSWE(t-1)>0;
SnowAge(t)=SnowAge(t-1)+0.04167;
else
SnowAge(t)=0;
end
end
if T(t)>273.16;
Z(t)=DPp;
else
Z(t)=DPn;
end
if Ps(t)>SS; %Albedo
Albedo(t)=Amin+Aadd;
if SnowAge(t)>0;
Albedo(t)=Amin+(Albedo(t-1)-Amin)*exp(Z(t)*0.04167);
else
Albedo(t)= 0;
end
end
SurfTemp(t)=min(T(t),273.16);
VapPresA(t)=6.1078*exp((17.08085*(T(t)-273.16))/(234.175+(T(t)-273.16)))*(Relhum(t)/100);
if ModeledSWE(t-1)>0;
VapPresS(t)=6.1078*exp((17.088085*(SurfTemp(t)-273.16))/(234.175+(SurfTemp(t)-273.16)));
else
VapPresS(t)=0;
end
ShortRadBal(t)=(1- Albedo(t))*GlobalRad(t);
LongRadBal(t)=Inlong(t)-(Se*SBC*SurfTemp(t)^4);
SenHeatFlux(t)=18.85*(0.18+0.098*Wind(t))*(T(t)-SurfTemp(t));
LatHeatFlux(t)=32.82*(0.18+0.098*Wind(t))*(VapPresA(t)-VapPresS(t));
if Pr(t)>0;
AdvFluxR(t)=SHCW*(T(t)-273.16)*Pr(t)/3600;
else
AdvFluxR(t)=0;
end
if Ps(t)>0;
AdvFluxS(t)=SHCS*(T(t)-273.16)*Ps(t)/3600;
else
AdvFluxS(t)=0;
end
EB(t)=ShortRadBal(t)+LongRadBal(t)+SenHeatFlux(t)+LatHeatFlux(t)+AdvFluxR(t)+AdvFluxS(t)+SHF;
if ModeledSWE(t-1)>0;
Sublim(t)=3600*LatHeatFlux(t)/CSH;
else
Sublim(t)=0;
end
if T(t)>273.16;
if ModeledSWE(t-1)>0 & EB(t)>0;
Melt(t)= min(EB(t)*3600/MH ,ModeledSWE(t-1));
else
Melt(t)=0;
end
else
Melt(t)=0;
end
if ModeledSWE(t-1)>0;
max((ModeledSWE(t-1)+Pr(t)+Ps(t)+Sublim(t)-Melt(t)),0);
else
max((Ps(t)+Sublim(t)-Melt(t)),0);
end
end

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采纳的回答

Roger Wohlwend
Roger Wohlwend 2016-2-4
Albedo(t) only exist if Ps(t) > SS. It seems that for k = 2 this condition is not met, the code in the if-clause is not execute and Albedo(2) is never calculated. That is why Albedo(2) does not exist and the error occurs. You can solve the Problem by introducting an else-clause
if Ps(t)>SS
Albedo(k) = something
else
Albedo(k) = something else
end
With every Iteration you increase the Albedo vector and several other vectors. That is not a good programming technique. I recommend preallocating Memory for all those vectors. That makes the code run faster. For more Information search for "Preallocation" in the Matlab documentary. In your case insert the following line before the Loop
Albedo = Zeros(length(P),1)
and repeat that for all other vectors (VapPresS, Sublim, Melt, ..). Then you can delete Albedo(1) = 0 (and Melt(1) = 0, Sublim(1) = 0, ...).
  2 个评论
Image Analyst
Image Analyst 2016-2-5
You're lucky Roger is trying to help you. Many people (like me) are not going to examine lengthy code like that unless it can be copied and pasted and run in the debugger, which it can't because you forgot to attach ESCIMOdata.dat.
hydrogall
hydrogall 2016-2-5
You're right. I am lucky to have had Roger's help as now my code is running perfectly. I am very appreciative of his help and grateful of those who take the time to teach a newbie. We all go through the learning curve.

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