The same script/funktion different time with MatLab

Question

i am somekind of "advanced" beginner in programing. I couldn't find answer to my question, i found this, MATLAB Speed Difference in Identical Code, but it is not exactly what i'm looking for. I have the following problem, my script or function consists of couple of segments, when i run them manually with Run Section, i need something like 15 sec. including scroling and clicking. When i start them as one function i need 72 sec. The code is:

a=diff(Min_ZR);
b=zeros(38000000,1)*NaN;
i=1;

while i<length(a)
if a(i)==1;
    b(i)=1;
    i=i+1;

else
    b(i)=0;
    i=i+1;
end
end


 b(i:end) = [];
%%
iL=2;
kL=2;
L1=zeros(38000000,1)*0;

while iL<length(test_L)

if test_L(iL)==1

L1(iL)=L1(kL-1)+1;
iL=iL+1;
kL=iL;
else
    L1(iL)=L1(iL-1);
    iL=iL+1;

end
end
L1(iL:end)=[];

%%

iR=2;
kR=2;
L2=zeros(38000000,1)*0;

while iR<length(test_R)

if test_R(iR)==1

L2(iR)=L2(kR-1)+1;
iR=iR+1;
kR=iR;
else
    L2(iR)=L2(iR-1);
    iR=iR+1;

end
end
L2(iR:end)=[];
%%

iZ=2;
kZ=2;
ZR=zeros(38000000,1)*0;

%while i<length(test_R)
while iZ<length(b)
if b(iZ)==1

ZR(iZ)=ZR(kZ-1)+1;
iZ=iZ+1;
kZ=iZ;
else
    ZR(iZ)=ZR(iZ-1);
    iZ=iZ+1;

end
end
ZR(iZ:end)=[];





%%
L1=L1/4;
L2=L2/4;
ZR=ZR/8*34/22;
i=1;
diff_L1=zeros(38000000,1)*NaN;
diff_L2=zeros(38000000,1)*NaN;
while i<=length(ZR)

diff_L1(i)=L1(i)-ZR(i);
diff_L2(i)=L2(i)-ZR(i);
i=i+1;
end
diff_L1(i:end)=[];
diff_L2(i:end)=[];

l=length(ZR);
Drehmoment=zeros(l,1);
Drehmoment(1:10000)=100;
Drehmoment(10001:end)=380;
%%

figure % new figure
[hAx,hLine1,hLine2] = plotyy(ZR,diff_L2,ZR,Drehmoment);

title('Zahnradwandern 30.03.2016')
xlabel('Gesamtumdrehungen /1 ')

ylabel(hAx(1),'Differenzumdrehungen /1 ') % left y-axis
ylabel(hAx(2),'Drehmoment / Nm') % right y-axis

set(hAx(1),'Xlim',[0 1050000])
set(hAx(2),'Xlim',[0 1050000])
set(hAx(1),'Xtick',0:50000:1050000)
set(hAx(1),'XTickLabel',{'0','','100000','','200000','','300000','','400000','','500000','','600000','','700000','','800000','','900000','','1000000',''})
set(hAx(1),'Ylim',[-2 38])
set(hAx(1),'YTick',-2:2:38)
set(hAx(2),'YTick',0:20:400)
set(hAx(2),'Ylim',[0 400])
grid on
hold on 
plot (ZR,diff_L1,'color','g')
hold off
legend('Differenzumdrehungen PL2','Differenzumdrehungen PL1','Antriebsmoment')

For each section i need less then 1 or 2 sec. just for the Plot i need a bit more, but as i wrote 15 sec. tops it is nowhere near to 72 sec. that i get when i Run the Function. Thank you in advance.

Also good information is, what can be inside variables mentioned by @StewieGriffin. Are they logical, integer, float,...? — Crowley
– Crowley, Commented Apr 27, 2016 at 9:53

GDD · Accepted Answer · 2016-04-27 12:09:14Z

0

I've found the Problem, if i start the program with run and time, it tells me 72 sec, or after i used hint 4. from Crowley 60 sec. It also says that the "Run and Time fkt" don't use resources but if i just Run the program it completes in under 10sec.

answered Apr 27, 2016 at 12:09

GDD

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1 Comment

hbaderts Over a year ago

With the MATLAB Profiler ("Run and Time"), the Just-in-Time Compiler (JIT) can not optimize certain things, such as for/while loops, which can make your code much slower.

Crowley · Accepted Answer · 2016-04-27 12:51:15Z

0

Does your code improve it's performance when:

you change indexes i to ii. i and j are reserved for imaginary units;
define b=nan(length(a),1); and L1=zeros(length(test_L),1); and ommit b(:,end)=[]; and L1(iL:end)=[];;
use for ii=1:length(a) instead of while loop;
use b=zeros(length(a),1);b(a==1)=1; instead of whole while loop;
use diff_L=L1-R1 instead of while loop;
use Drehmoment=ones(l,1)*380;Drehmoment(1:100000)=100;?

These are just suggestions where you can loose your time...

EDIT regarding to hbadert's comment

Have you tried:

Block=1;
BlockTic(Block)=tic;
%%Block 1
BlockToc(Block)=toc;
Block=Block+1;
BlockTic(Block)=tic;
%%...
BlockToc(Block)=toc;

AllTime=BlockToc(end)-BlockTic(1);
Times=BlockToc-BlockTic;

disp(['Global time: ',num2str(AllTime)])
disp('Block times:')
disp(Times')

edited Apr 27, 2016 at 12:51

answered Apr 27, 2016 at 9:58

Crowley

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10 Comments

GDD Over a year ago

I think you don't understand my question. I hope you see the different Sections, if i run just a section any of them they take 0,5 sec. i'm pretty sure they are as fast as they can be. I can run the whole code in under 10sec if i run them "sectionwise" and if i run the whole program it goes slowly in 72 secs to be exact. I do not think it has anything to do with the name of my variables. @Crowley thx i use 4 instead of my loop :) 5 is not bad idea, i use the loop because the length of LR and ZR is not the same.

Crowley Over a year ago

Using ii instead of i is like driving on the right side of the road (unless you are japaneese, english,...). You can drive a car on the left side without any problem for years; untill you meet someone driving against you...

Crowley Over a year ago

2nd and 6th poit may improve readability and may reduce memory usage because of proper allocation of variables.

Crowley Over a year ago

Why are LR and ZR of different dimension? Maybe you can use diff(LR(1:M),ZR(1:M)) where M=min([length(LR),length(ZR)]);

Crowley Over a year ago

You also don't need to use unique counters for every loop, you can use only ii, jj, kk counters for whole m-file.

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