MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn moreOpportunities for recent engineering grads.

Apply Today**New to MATLAB?**

Asked by Mohsen
on 17 Jun 2013

Does any one know how to optimize this code so that it runs faster:

for i=1:iNZ; if iPointsinSlice>0; for m=1:iNX; for l=1:iNY; if SliceMaskUr(m,l)==1; DoseCubeU(m+(l-1)*iNX+i*iNX*iNY)=100*SumDose(m,l,i)/RX_Dose; end end end end end

Your help is much appreciated! Thanks a lot!

Answer by Roger Stafford
on 17 Jun 2013

Is 'iPointsinSlice' a scalar? If so and if it is not positive, nothing will happen here.

Next, don't you mean "m+(l-1)*iNX+(i-1)*iNX*iNY" as the index to 'DoseCubeU'? As it stands it will vary from 1+iNX*iNY to iNX*iNY*iNZ+iNX*iNY. Assuming my guess is correct, do this:

if iPointsinSlice > 0 t = repmat(SliceMaskUr==1,1,1,iNZ); DoseCubeU(t) = (100/RX_Dose)*SumDose(t); end

In case 'iPointsinSlice' is not a scalar you will have to correct your code before we can see how to handle it.

Answer by Roger Stafford
on 17 Jun 2013

Sorry! It should have been:

t = repmat(SliceMaskUr==1,[1,1,iNZ]);

Mohsen
on 18 Jun 2013

I changed

DoseCubeU(m+(l-1)*iNX+i*iNY*iNX)=100*SumDose(m,l,i)/RX_Dose;

to

DoseCubeU(double(m)+double((l-1))*double(iNX)+double((i-1))*double(iNY)*double(iNX))=100*SumDose(m,l,i)/RX_Dose;

Otherwise the indexing will not be correct. For example, iNX*iNY*iNZ (which is 120*120*11) becomes equal to 65535 (which is wrong). We should write it as double(iNX)*double(iNY)*double(iNZ) in order to get the correct results (ie. 158400).

By making this change, both the indexing (the initial) method and the subscription method (below) give the same results. But these results are different than any of the other proposed methods.

So, how can I optimize:

for i=1:iNZ; if iPointsinSlice>0; for m=1:iNX; for l=1:iNY; if SliceMaskUr(m,l)==1; DoseCubeU(m,l,i)=100*SumDose(m,l,i)/RX_Dose; end end end end end

Answer by Mohsen
on 17 Jun 2013

This code doesn't give me the same result as my initial code. Please note that the purpose of "m+(l-1)*iNX+i*iNX*iNY" is to reshape the SumDose array which is (iNX by iNY by iNZ) to a one dimensional array (1 by iNX*iNY*iNZ).

I tried also

if SliceMaskUr==1; DoseCubeU= reshape(SumDose,1,[iNX iNY iNZ])*(100/RX_Dose); end

but it didn't work neither...

Any insight?

Show 1 older comment

Mohsen
on 18 Jun 2013

Thank you for your reply. In my original code, I changed "m+(l-1)*iNX+i*iNX*iNY" to "m+(l-1)*iNX+(i-1)*iNX*iNY" so that the index of DoseCubeU is from 1 to iNX*iNY*iNZ.

Both DoseCubeU and SumDose are of sizes iNX-by-iNY-by-iNZ.

However, your code still gives me a different answer than my original code.

As a test, in order to use the subscription notation instead of indexing, I just modified my code to the following and surprisingly the results are again different from the two previous methods:

for i=1:iNZ; if iPointsinSlice>0; for m=1:iNX; for l=1:iNY; if SliceMaskUr(m,l)==1; DoseCubeU(m,l,i)=100*SumDose(m,l,i)/RX_Dose; end end end end end

This is confusing!!

Mohsen
on 18 Jun 2013

I think that the function poly2mask is in charge of these discrepancies. Any idea why? Here is the entire code:

iNNX=double(iNX);

iNNY=double(iNY);

for i=1:iNZ;

iPointsinSlice=1;

for j=1:iNCUr; if UrContourZ(j)==ZSlice(i); iPointsinSlice = iPointsinSlice+1; UrPointX(iPointsinSlice-1)=1 + (UrContourX(j)-Offset(1,1)); UrPointY(iPointsinSlice-1)=1 + (UrContourY(j)-Offset(2,1)); end end

if iPointsinSlice>0; indx=round(iPointsinSlice); indy=round(iPointsinSlice);

indx(1:iPointsinSlice-1)=UrPointX(1:iPointsinSlice-1)/DresX; indy(1:iPointsinSlice-1)=UrPointY(1:iPointsinSlice-1)/DresY;

SliceMaskUr = poly2mask(indx,indy,iNNX,iNNY);

for m=1:iNX; for l=1:iNY; if SliceMaskUr(m,l)==1; DoseCubeU(m+(l-1)*iNX+(i-1)*iNY*iNX)=100*SumDose(m,l,i)/RX_Dose; end end end end end

Your help is much appreciated! :)

Mohsen
on 18 Jun 2013

I changed

DoseCubeU(m+(l-1)*iNX+i*iNY*iNX)=100*SumDose(m,l,i)/RX_Dose;

to

DoseCubeU(double(m)+double((l-1))*double(iNX)+double((i-1))*double(iNY)*double(iNX))=100*SumDose(m,l,i)/RX_Dose;

Otherwise the indexing will not be correct. For example, iNX*iNY*iNZ (which is 120*120*11) becomes equal to 65535 (which is wrong). We should write it as double(iNX)*double(iNY)*double(iNZ) in order to get the correct results (ie. 158400).

By making this change, both the indexing (the initial) method and the subscription method (below) give the same results. But these results are different than any of the other proposed methods.

So, how can I optimize:

for i=1:iNZ; if iPointsinSlice>0; for m=1:iNX; for l=1:iNY; if SliceMaskUr(m,l)==1; DoseCubeU(m,l,i)=100*SumDose(m,l,i)/RX_Dose; end end end end end

Answer by Andrei Bobrov
on 18 Jun 2013

Edited by Andrei Bobrov
on 19 Jun 2013

DoseCubeU = bsxfun(@times,100*SumDose/RX,SliceMaskUr==1);

ADD

s = SliceMaskUr(end:-1:1,end:-1:1); tt = cumsum(cumsum(s),2); t1 = flipud(any(tt,2)); t2 = fliplr(any(tt)); DoseCubeU = bsxfun(@times,100*SumDose(t1,t2,:)/RX_Dose,SliceMaskUr(t1,t2));

Show 1 older comment

Mohsen
on 18 Jun 2013

I think that the function poly2mask is in charge of these discrepancies. Any idea why? Here is the entire code:

iNNX=double(iNX);

iNNY=double(iNY);

for i=1:iNZ;

iPointsinSlice=1;

for j=1:iNCUr; if UrContourZ(j)==ZSlice(i); iPointsinSlice = iPointsinSlice+1; UrPointX(iPointsinSlice-1)=1 + (UrContourX(j)-Offset(1,1)); UrPointY(iPointsinSlice-1)=1 + (UrContourY(j)-Offset(2,1)); end end

if iPointsinSlice>0; indx=round(iPointsinSlice); indy=round(iPointsinSlice);

indx(1:iPointsinSlice-1)=UrPointX(1:iPointsinSlice-1)/DresX; indy(1:iPointsinSlice-1)=UrPointY(1:iPointsinSlice-1)/DresY;

SliceMaskUr = poly2mask(indx,indy,iNNX,iNNY);

for m=1:iNX; for l=1:iNY; if SliceMaskUr(m,l)==1; DoseCubeU(m+(l-1)*iNX+(i-1)*iNY*iNX)=100*SumDose(m,l,i)/RX_Dose; end end end end end

Your help is much appreciated! :)

Mohsen
on 18 Jun 2013

I changed

DoseCubeU(m+(l-1)*iNX+i*iNY*iNX)=100*SumDose(m,l,i)/RX_Dose;

to

DoseCubeU(double(m)+double((l-1))*double(iNX)+double((i-1))*double(iNY)*double(iNX))=100*SumDose(m,l,i)/RX_Dose;

Otherwise the indexing will not be correct. For example, iNX*iNY*iNZ (which is 120*120*11) becomes equal to 65535 (which is wrong). We should write it as double(iNX)*double(iNY)*double(iNZ) in order to get the correct results (ie. 158400).

By making this change, both the indexing (the initial) method and the subscription method (below) give the same results. But these results are different than any of the other proposed methods.

So, how can I optimize:

Answer by Iain
on 18 Jun 2013

Try:

DoseCubeU(NY,NX,NZ) = 0; % or any suitable initialisation if iPointsinSlice>0; DoseCubeU(SliceMaskUr(m,l)==1,:) = 100*SumDose(SliceMaskUr(m,l)==1,:); end

Mohsen
on 18 Jun 2013

I changed

DoseCubeU(m+(l-1)*iNX+i*iNY*iNX)=100*SumDose(m,l,i)/RX_Dose;

to

So, how can I optimize:

## 0 Comments