Faulty result on contour map

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Volkan Yangin
Volkan Yangin on 29 Nov 2016
Commented: Volkan Yangin on 3 Dec 2016
I have just created a contour map, but some values are false. I don't know where is my error? May you help me? My dataset at the attachment.
data=xlsread('data.xlsx')
rpm=xlsread('data.xlsx','A3:A10')
kw=xlsread('data.xlsx','B2:I2')
bsfc=xlsread('data.xlsx','B3:I10')
a = surf(rpm, kw, bsfc);
[a,b] = contourf(rpm, kw, bsfc);
clabel(a,b);
xlabel('rpm');
ylabel('kW');
  2 Comments
Walter Roberson
Walter Roberson on 30 Nov 2016
Could you be more specific about the areas that are "false"? The only difficulty I see is the way the 250 has a branch that ends abruptly.
Which MATLAB release are you using?
Have you tried setting the figure renderer to different things, zbuffer and painters and opengl ?
Volkan Yangin
Volkan Yangin on 30 Nov 2016
For example, at 2000 rpm and 60 kw, BSFC value must be 0, but the same point on the contur graph shows this point as 350 g/kWh.
I am using MATLAB 2008 and i didn't try anything about this process.

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Answers (1)

Daniel kiracofe
Daniel kiracofe on 30 Nov 2016
Not 100% sure what you mean by "some values are false", but I suspect that you've just transposed x and y axis. Does
a = surf(kw,rpm, bsfc);
[a,b] = contourf(kw, rpm, bsfc)
do what you want?
If not, then please elaborate on what you don't like about the graph and what you think it should look like.
  4 Comments
Guillaume
Guillaume on 30 Nov 2016
You should accept Daniel's answer to give him credit and to tell others that it is now solved.
A fuel consumption of 0 at high load? I want your engine! Or perhaps the BSFC should be NaN instead of 0 to indicate that the particular test point was not tested / could not be reached.
Volkan Yangin
Volkan Yangin on 3 Dec 2016
Thank you Guillaume At the lessons, we write 0 at over of the full load curves. So, i wrote as 0, too.

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