function?[Bp?Im]=ffbp_for_david_pearce（Sim?Pos?Bp?f）

%FFBP?Fast?factorised?backprojection?of?synthetic?aperture?sonar?data
%
%?Usage:?[Bp?Im]=ffbp（Sim?Pos?Bp?f）
%
%??Sim:?struct?containing?important?information?about?the?simulation?/?raw?data.
%
%??Bp:?struct?containing?important?information?about?the
%??backprojection.
%
%??Pos:?struct?containing?the?positions?of?the?transmitter?and?the
%??receivers.
%??
%??See?params_for_ffbp.m?for?a?description?of?the?required?fields?in?Sim
%??Bp?and?Pos.
%
%??f:?matrix?containing?the?raw?data.
%
%??Im:?resulting?image
%

tic

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%---------Main---------------------------------
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[Fact?Bp?Im?f]=pre_allocate（Sim?Bp?Pos?f）;
[Sim?Bp?Fact?f]=stages（Fact?Sim?Bp?Pos?f）;
[Im?Bp]=last_stage（Fact?Sim?Bp?Pos?f?Im）;
toc
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%----------------------------------------------
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%---------stages-----------------------------------
function?[Sim?Bp?Fact?f]=stages（Fact?Sim?Bp?Pos?f）
Fact.stage=0;
Bp.error=0;
Fact.noSubimages=0;
Fact.min_range_old（1:Bp.Q_image（1）^2）=Sim.y_image_start;
Fact.parent（1:Bp.Q_image（1）^2）=[1:Bp.Q_image（1）^2];
if?strcmp（Bp.weighting?‘ones‘）?%Setting?weights
????Bp.w（1:Fact.noReceivers）=ones（1?Fact.noReceivers）;
else
????Bp.w（1:Fact.noReceivers）=eval（strcat（Bp.weighting‘（Fact.noReceivers）‘））;
end?%if?strcmp（Bp.weighting?‘ones‘）

for?s=Fact.stage+1:Bp.totalNoStages-1
????Fact.stage=Fact.stage+1;
????disp（[‘-----------------------------------‘]）
????disp（[‘Stage=‘?num2str（Fact.stage）]）
????sc=1;?%Subimage?count
????Fact.E=prod（Bp.Q_image（1:Fact.stage））;?%Number?of?subimages?on?each?side
????
????Fact.noSubimages=Fact.E^2;?%Total?number?of?subimages?in?the?current?stage
????
????Bp.error=Bp.error+（（（Fact.xReceivers（12）-Fact.xReceivers（11））*Bp.Q_receivers（s）*Bp.xImageLength/Fact.E）/（4*Bp.y_image_start））;
????
????disp（[‘Error?must?be?less?than?lambda/4‘]）
????disp（[‘Error=lambda/‘num2str（Sim.lambda/Bp.error）]）
????if?Sim.lambda/Bp.error<=4
????????disp（[‘Approximation?error?to?large!‘]）
????else
????????disp（[‘Approximation?error?OK‘]）
????end
????if?Bp.error>Bp.highest_error
????????Bp.highest_error=Bp.error;
????end
????disp（[‘Number?of?subimages=‘num2str（Fact.noSubimages）]）
????disp（[‘Number?of?receivers=‘num2str（Fact.noReceivers）]）
????Fact.xEdges=Bp.x_image_start:（Bp.x_image_stop-Bp.x_image_start）/Fact.E:Bp.x_image_stop;?%Edges?of?the?subimages?in?x-direction?[m]
????Fact.yEdges=Bp.y_image_start:（Bp.y_image_stop-Bp.y_image_start）/Fact.E:Bp.y_image_stop;?%Edges?of?the?subimages?in?y-direction?[m]
????xMiddle=Bp.x_image_start+0.5*（Fact.xEdges（2）-Fact.xEdges（1））:Fact.xEdges（2）-Fact.xEdges（1）:Bp.x_image_start+0.5*（Fact.xEdges（2）-Fact.xEdges（1））+（Fact.E-1）*（Fact.xEdges（2）-Fact.xEdges（1））;?%Middle?point?of?the?subimages?in?x-direction?[m]
????yMiddle=Bp.y_image_start+0.5*（Fact.yEdges（2）-Fa

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件???????11049??2012-06-15?11:15??ffbp.m
?????文件????????1633??2012-06-15?11:15??params_for_ffbp.m