## Ramakrishnan

Dr. Ramakrishnan Vaidyanathan

## 259 Reputation

4 years, 360 days

## Social Networks and Content at Maplesoft.com

I have retired as Professor-Mechanical in Sri Venkateswara College of Engineering and Technology under Anna University affiliated colleges in Tamil Nadu, India. I have 19 years of Industrial and 20 years of teaching experience. I am learning Maple for the past four and half years hoping to make at least one appreciable maple presentation.

## How to delete yourself!...

Dear group member,

In the first place, I request you not to react immediately to my my message. The caption and the message are contradicting as it indicates that there is a maple account and there is another account of yours in the group. Let me not take this issue at all.

I also felt like deleting myself from different groups, but after me getting deleted (not myself, but by the group itself), I felt bad with an inferiority complex.

Ask yourself, what was your expectation when you joined the group. Certainly we were not and in fact no one, was an expert in maths and maple at the time of joining the group. Therefore the purpose was mainly to learn and share peer views apart from many other like getting good friends and knowing solutions to problems that we did not even know existed in maths.

I was doing a probe why I should quit?

First, I thought I am unfit and did not understand anything in the questions and answers. Then my mind said that is the main reason you should still continue in the group to improve yourself over time.

Next, I thought I am much superior to those participating in the group and know every thing. Then again my mind said that is main reason you should still continue in the group to contribute your approach to solutions, get pride and win thousands of hearts .

Either way, I find no reason why I should delete myself wheen I donot know how to do now Wait. Watch. You will see the light and bright future ahead. All the best.

Ramakrishnan V

## function application vs indexing...

Thanks.

Now I understand the difference between the use of open brackets and square brackets.

Thanks again.

Ramakrishnan V

Just have a procedure to vary the range till y approximately equal to zero (y < 1 e -12).

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## How Do I plot?...

Hope attached doc helps you to an extent. Please note, the function values, only you can determine with values of constants and variable r values.

Let r = r1, r2, r3, r4 and r5

At r, find V and E0

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Plot of V vs E0 is given below. Only points are plotted

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Plot of V vs B0 is given below.

Plot of V vs E0 is given below.

Similarly, find E0*B0 as a list and plot as below

Cheers. Ramakrishnan V

## Great...

it is great. Nice way for using it in a session. But any way out for only few lines in a session?

Cheers. Thanks.

Ramakrishnan V

## Equn label removal...

Dear Christopher, Thank you for the tips. It works and label are not visible. I also unselected [ Format -> Equation Labels -> Worksheet] and labels were removed.

I was wondering how the equations (two cells) between 10 and 11 and two equations (cells) were not included. I found the after typing the assignment command, if "ctrl+equal" to is entered, label  is not coming. If i use just "enter", then equan label comes out. I donot know if it is proper that way only or not.

In your recommendation, i believe no labels are provided for all lines (all labels are removed). If a few labels are needed and a few are not needed, then,i just wanted to know wheter use of " ctrl+equal " for no label  and " enter key " for label requirement are ok or not. There must be a way out in maple for this. I am just searching for it.

Thanks for you tips again as it works well for me.

Cheers. Ramakrishnan V

## working file...

Hope the contents of file enclosed will be ok.

Ramakrishnan VExperimentalData.xlsxRequest_Plot_from_ProfKitonum.mw

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## Information provided...

Dear Kitonum,

BP is brake power in kW, D4 EFF is efficiency value for model with 4 mm Dia orifice for a particular  say 5%EGR (P5) and with Cooling (P5C) or without cooling (P5U).

A curve needs to be obtained for each model for each parameter (Efficiency here).

I enclose the doc new one which works, but feel needs improvement.

Regarding the errors, I found out of the many,  two of them made here were

d[i] has in its first pair, strings [["BrakePower", "S2"],[x1,y1]...]. Hence an error

M1 could not be assigned because import file was open without saving in my PC. I closed it and then it was fine.

-15
-2.99760216648792 10    + 1.00000000000000 x
-16  2
+ 3.88578058618805 10    x
The above answer is incorrect. For S2 one equation and S4 another equation are required.

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The above answer is incorrect. For S2 one equation and S4 another equation are required.

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Thanks.

## Mistakes made - where i donot know...

Comparison of Performance of Two-Stroke Engine with Four-Stroke Engine

Brake Power Vs Brake Efficiency

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Comparison of Performance of Two-Stroke Engine with Four-Stroke Engine

Brake Power Vs Brake Efficiency

Comparison of Performance of Two-Stroke Engine with Four-Stroke Engine

Brake Power Vs Brake Efficiency

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Comparison of Performance of Two-Stroke Engine with Four-Stroke Engine

Brake Power Vs Brake Efficiency

The following recommended code with matrix A defined, gives me a single equation whereas my antincipation was for >1. I cld not workout the way it worked. Please do find the mistakes if possible. Thanks.

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Thank you.

Ramakrishnan V

## Interesting Technique...

The technique of defining the funations using an intermediate function g is quite wonderful.

Could you please explain in a few more lines as to how this is performed. Maple understands quite well! But i am still wondering how no error is shown for x1,y1,x2,y2. Is it because assignments are done prior to always.

How the functions f1, f2, f3 are not altered to, i wonder, though an interpolation g comes in between? Is there any accuray loss in this way?

or f1 f2 f3 are just a list of two end points and hence a set of straightlines will be always?

Just want to know, whether i am clear in my understanding.

Thanks.

Ramakrishnan V

## @tomleslie  Thank you very much. I...

Thank you very much. I was not aware of that assignment till now. Here after, i shall be doubly careful when i see an = sign!

Thanks for spending your valuable time and saving my time as well in quickly removing the error.

Ramakrishnan V

## Doubt on floattype(8) error and colour d...

I could get in two methods? Why the error in the first method below? Thanks for answering.

Ramakrishnan V

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How do I correct the error above?

Thanks.

Ramakrishnan V

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How do I change colour above here?

Thanks for help.

Ramakrishnan V

 > dataDF := DataFrame( < 1.9, 1.7, 3.0; 1.8, 1.5, 1.7; 3.2, 2.2, 3.1;2.2, 1.9, 3.2; 2, 1.7, 1.9; 3.3, 2.3, 3.2>, 'rows' = [ 'r1','r2','r3','r4','r5','r6'], 'columns' = [ 'c1', 'c2', 'c3'] ):
 > colorDF := DataFrame( < yellow,green,black; yellow,green,black;yellow,green,black;yellow,green,black; yellow,green,black;yellow,green,blue >, 'rows' = [ 'r1','r2','r3','r4','r5','r6'], 'columns' = [ 'c3', 'c1', 'c2'] ):

## Is Bar plot possible if xy combinations ...

Dear Prof., Thank you so much. [4,10,2] is right as you mentioned. I also did not mention that x and y are references and numbers as such. 4 mm diameter(x) with 10% recirculation(y) for cooled exhausr recirculation case(A) is referred to as case A [4,10, z] in which case please recommend a suitable command for (column) chart which is easy to visualise given a proper scale and width of each column.

Is it ok if i assume COLA [col1 is A 4 5,; col2 is A 4 10; col3 is A 4 15; ]

COLB[col4 is A 6 5,; col5 is A 6 10; col6 is A 6 15;]

COLC [col7 is A 8 5,; col8 is A 8 10; col9 is B 8 15; ]

COLE [col10 is B 4 5,; col11 is B 6 5; col2 is B 8 5;]

COLF [col13 is B 4 10,; col14 is B 6 10; col15 is B 8 10; ]

COLG

COLA to COLG are defined as A to G (D omitted)

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The chart i want is different in 6 groups and not 3 groups. Colour also i need to change. Please do help me with right commands. Thanks.

Ramakrishnan v

 Effect of A and B on z values Cooled Recirculation Uncooled Recirculation x                y 5% EGR 10% EGR 15% EGR 5% EGR 10% EGR 15% EGR 4 mm 6 mm 8 mm
Table 1: Effect of Modified Parameters on z output

Dear Prof.,
Thank you for your answer given below. It helped me understand simple ideas. I want a suitable plot for the above data. I have given the values as [ x  y  z] for z values to be plotted for the two cases, A and B in the same graph to compare and get the best option x ,    y and A or B .

Mathematically an x vs y vs z plot. Any bar or similar plot is what seems suitable to me.

I could not locate any help for plotting 3D data values in help page.

Thanks.

Ramakrishnan V

 > with(plots): Avals:= [ [ 4, 5, 1.9],  [ 6, 5, 1.7],  [ 8, 5, 3.0],           [ 4, 10, 1.8], [ 6, 10, 1.5], [ 8, 10, 1.7],           [ 4, 15, 3.2], [ 6, 15, 2.2], [ 8, 15, 3.1]         ]: Bvals:= [ [ 4, 5, 2.2],  [ 6, 5, 1.9],  [ 8, 5, 3.2],           [ 4, 5, 2.0],  [ 6, 10, 1.7], [ 8, 10, 1.9],           [ 4, 15, 3.3], [ 6, 15, 2.3], [ 8, 15, 3.2]         ]: p1:=pointplot3d(Avals, symbol=sphere, symbolsize=20, color=red): p2:=pointplot3d(Bvals, symbol=sphere, symbolsize=20, color=blue): display([p1, p2]);

[col16 is B 4 15,; col7 is B 6 15; col8 is B 8 15;]

Your answer has given me the way to proceed in a simpler way for the combinations i have. After seein the plot in your doc only, i realised that giving values to x and y is a gross mistake because point plots show scattered points and difficult to notice the corresponding optimum case combination. Thank you again. Ramakrishnan V

## just sending result from maple2017...

Hope attached doc gives some hope.Just typed in 2017 and sending you the error msg.

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