Fill up area between 2 circles

Bapak Ireng

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Jul 10, 2023, 9:19:28 AM7/10/23

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Dear Helmut,

after a long time I do have again a question on how to achieve filling up the area between 2 circles - only 180 degree. To be able to achive this task with one call of a subroutine, will there be a special subroutine availble or do I have to create the intermediate points with means of a special routine ?

Regards, Bapak ireng

Helmut Michels

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Jul 14, 2023, 6:05:43 AM7/14/23

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Dear Bapak,

sorry, there is no routine for doing this automatically. You have to calculate the area between the circles

and plot it with a polygon filling routine of Dislin. For example with areaf.

With best regards,

Helmut

Bapak Ireng

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Jul 17, 2023, 3:16:18 AM7/17/23

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Hello and good morning dear helmut,

many thanks for your kind and valuable answer.

My programs are in F90.

I used the subroutine circle to draw 2 circles perfectly from -90 to +90 degree with radius1 < radius2.

With xm and ym as being the centre of the circle, i was able to calculate the coordinates of the inner and outer circle and used a polygon filling routine in a second run, as suggested by you.

However, the results looks very weird. Only at the horizontal line ( 0 Degree) is a match, all other of my coordinates are far below the circles drawn by the subroutine circle.

Real, Parameter :: wd0=-90.

do i=0,179

wd=(wd0+float(i))

x1(i+1)=xm+(rad1*cos(wd))
y1(i+1)=ym+(rad1*sin(wd))

x2(i+1)=xm+(rad2*cos(wd))
y2(i+1)=ym+(rad2*sin(wd))

end do

Does the subroutine circle uses degree or polar coordinates ?

Best regards, Bapak Ireng

Bapak Ireng

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Jul 17, 2023, 3:32:15 AM7/17/23

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Dear Helmut,

is there any way to access the calculated coordinates of the subroutine circle ?

best regards, BApak Ireng

Helmut Michels

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Jul 17, 2023, 6:22:19 AM7/17/23

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Hi,

no, but the circle is calculated in the same way as in your example above. Note, that the

origin of the page is in the upper left corner if you are using plot coordinates, and not world

coordinates in an axis system.

With best regards,

Helmut

Helmut Michels

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Jul 17, 2023, 6:22:32 AM7/17/23

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Hi Bapak,

the Fortran functions cos and sin use radian instead of degree.

With best regards,

Helmut

Bapak Ireng

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Jul 17, 2023, 6:31:26 AM7/17/23

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Hi,

thanks for your answer.

I am using an axis system (0,1000, 0, 1000) to be able to construct the image.

Therefore all coordinates are in between these values.

best regards,

Bapak Ireng

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Jul 17, 2023, 7:00:15 AM7/17/23

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Bildschirmfoto vom 2023-07-17 12-57-36.png

Thats what the result of the calculated coordinates look like.

Best regards, Bapak ireng

Bapak Ireng

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Jul 18, 2023, 5:57:34 AM7/18/23

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Any suggestion what happened and why it looks like this ?

Helmut Michels

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Jul 18, 2023, 10:03:12 AM7/18/23

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Dear Bapak,

the size axis system is not quadratic I think. Dislin plots circles in axis systems by converting world

coordinates to plot coordinates, so that a circle everytime looks like a circle. The x scaling is used for

caculating the radius of a circle. You can take a look at the attached example code, that does nearly what

you want.

With best regards,

Helmut

t1.f90

dislin.png

Bapak Ireng

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Jul 19, 2023, 3:54:11 AM7/19/23

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dear Helmut,

thank you very much for your valubale input and contribution. I am still in the process of debugging my coding.
As son as I resolved my issue, i will come back to you.

Best regards, Bapak Ireng

Bapak Ireng

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Jul 21, 2023, 9:05:01 AM7/21/23

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Dear Helmut,

your sample program works perfect. However as soon as i incorporate your calculation of IXM, IYm, nr1 and nt2 into my progam it is still a complete mess..sayind data out of range.

call graf(0.,1000.,0.,100.,0.,1000.,0.,100.)

xm=530

YM=560

Rad1=30

Rad2=40

with this data

im=nxosn(xm)

iym=nyposn(ym)

IXM= 1543

IYM= 1016

Nrad1= 59

Nrad2= 79

which is far beyond the limits of the plot data.

Best regards,

Bapak Ireng

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Jul 21, 2023, 9:37:39 AM7/21/23

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Typo:

ixm=nxposn(xm)

Bapak Ireng

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Jul 21, 2023, 10:44:31 AM7/21/23

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Bildschirmfoto vom 2023-07-21 16-41-27.png

That show it loks like withe the adjusted radius and orginal Xm, Ym. The values of the adjusted Xm,Ym are out of range.

Bapak Ireng

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Sep 24, 2023, 11:26:23 PM9/24/23

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Dear Helmut,

sorry that I am getting back to you now. I was very busy lately and I had no time to continue on my project.

However, I would like to tell you, that your sample presents the perfect solution and I finally found out my mistake, by usin the wrong plotting subroutine.