How to calculate Area under a curve (negatif side)
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Ceren Memis
am 24 Jan. 2022
Kommentiert: Star Strider
am 26 Jan. 2022
I have a dataset and I made it curve. I want to calculate the area (like result_2) of the curve but I get a result like the picture on the result_1. Is there anyone who can help with this issue?
f = [-0.390930468901234 -0.346778353936444 -0.304499753808231 -0.264063453713497 -0.225438238849140 -0.188592894412060 -0.153496205599158 -0.120116957607333 -0.0884239356334846 -0.0583859248745134 -0.0299717105273190 -0.00315007778880116 0.0221101881441402 0.0458403020746052 0.0680714788056940 0.0888349331405067 0.108161879882144 0.126083533833705 0.142631109798290 0.157835822579000 0.171728886978934 0.184341517801193 0.195704929848877 0.205850337925086 0.214808956832921 0.222612001375480 0.229290686355865 0.234876226577176 0.239399836842512 0.242892731954974 0.245386126717662 0.246911235933676 0.247499274406116 0.247181456938083 0.245988998332677 0.243953113392996 0.241105016922143 0.237475923723217 0.233097048599318 0.227999606353545 0.222214811789001 0.215773879708783 0.208708024915994 0.201048462213732 0.192826406405098 0.184073072293192 0.174819674681114 0.165097428371965 0.154937548168844 0.144371248874851 0.133429745293087 0.122144252226652 0.110545984478646 0.0986661568521688 0.0865359841503211 0.0741866811762028 0.0616494627329141 0.0489555436235550 0.0361361386512258 0.0232224626190266 0.0102457303300567 -0.00276284341258221 -0.0157720438057912 -0.0287506560464691 -0.0416674653315173 -0.0544912568578337 -0.0671908158223202 -0.0797349274218757 -0.0920923768533994 -0.104231949313792 -0.116122429999953 -0.127732604108783 -0.139031256837181 -0.149987173382047 -0.160569138940281 -0.170745938708783 -0.180486357884452 -0.189759181664190 -0.198533195244895 -0.206777183823467 -0.214459932596806 -0.221550226761814 -0.228016851515387 -0.233828592054427 -0.238954233575834 -0.243362561276507 -0.247022360353347 -0.249902416003253 -0.251971513423126 -0.253198437809864 -0.253551974360368 -0.253000908271538 -0.251514024740273 -0.249060108963473 -0.245607946138040 -0.241126321460871 -0.235584020128867 -0.228949827338928 -0.221192528287954 -0.212280908172844]
t = linspace(0,100,100);
sinus_f = sin(f)
plot(t,sinus_f)
min_f = find(islocalmin(sinus_f));
max_f = find(islocalmax(sinus_f));
axis tight
P1_1 = gca; % gca creates a cartesian axes object
P1_1.XAxisLocation = 'origin'
hold on
basevalue_A1 = 1;
xline(t(min_f),'--b')
yline(sinus_f(min_f),'--r')
xline(t(max_f),'--b')
yline(sinus_f(max_f),'--r')
area_A1 = area(t(max_f:min_f),sinus_f(max_f:min_f),'FaceColor','g') % the area by points
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Star Strider
am 24 Jan. 2022
Bearbeitet: Star Strider
am 24 Jan. 2022
Try ths —
f = [-0.390930468901234 -0.346778353936444 -0.304499753808231 -0.264063453713497 -0.225438238849140 -0.188592894412060 -0.153496205599158 -0.120116957607333 -0.0884239356334846 -0.0583859248745134 -0.0299717105273190 -0.00315007778880116 0.0221101881441402 0.0458403020746052 0.0680714788056940 0.0888349331405067 0.108161879882144 0.126083533833705 0.142631109798290 0.157835822579000 0.171728886978934 0.184341517801193 0.195704929848877 0.205850337925086 0.214808956832921 0.222612001375480 0.229290686355865 0.234876226577176 0.239399836842512 0.242892731954974 0.245386126717662 0.246911235933676 0.247499274406116 0.247181456938083 0.245988998332677 0.243953113392996 0.241105016922143 0.237475923723217 0.233097048599318 0.227999606353545 0.222214811789001 0.215773879708783 0.208708024915994 0.201048462213732 0.192826406405098 0.184073072293192 0.174819674681114 0.165097428371965 0.154937548168844 0.144371248874851 0.133429745293087 0.122144252226652 0.110545984478646 0.0986661568521688 0.0865359841503211 0.0741866811762028 0.0616494627329141 0.0489555436235550 0.0361361386512258 0.0232224626190266 0.0102457303300567 -0.00276284341258221 -0.0157720438057912 -0.0287506560464691 -0.0416674653315173 -0.0544912568578337 -0.0671908158223202 -0.0797349274218757 -0.0920923768533994 -0.104231949313792 -0.116122429999953 -0.127732604108783 -0.139031256837181 -0.149987173382047 -0.160569138940281 -0.170745938708783 -0.180486357884452 -0.189759181664190 -0.198533195244895 -0.206777183823467 -0.214459932596806 -0.221550226761814 -0.228016851515387 -0.233828592054427 -0.238954233575834 -0.243362561276507 -0.247022360353347 -0.249902416003253 -0.251971513423126 -0.253198437809864 -0.253551974360368 -0.253000908271538 -0.251514024740273 -0.249060108963473 -0.245607946138040 -0.241126321460871 -0.235584020128867 -0.228949827338928 -0.221192528287954 -0.212280908172844]
t = linspace(0,100,100);
sinus_f = sin(f)
plot(t,sinus_f)
min_f = find(islocalmin(sinus_f));
max_f = find(islocalmax(sinus_f));
axis tight
P1_1 = gca; % gca creates a cartesian axes object
P1_1.XAxisLocation = 'origin'
hold on
basevalue_A1 = 1;
xline(t(min_f),'--b')
yline(sinus_f(min_f),'--r')
xline(t(max_f),'--b')
yline(sinus_f(max_f),'--r')
Lv = t<=t(min_f) & t>=t(max_f);
AUC = trapz(t(Lv), sinus_f(Lv));
text(40, -0.1, sprintf('AUC = %.6f', AUC))
area_A1 = patch([t(Lv) flip(t(Lv))], [ones(size(t(Lv)))*sinus_f(min_f) flip(sinus_f(Lv))], 'g', 'FaceAlpha',0.25);
% area_A1 = area(t(max_f:min_f),sinus_f(max_f:min_f),'FaceColor','g') % the area by points
EDIT — (24 Jan 2022 at 18:18)
Added ‘AUC’ calculation and text display.
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