why should we use excel 6

[MALY]

I would like to ask all of you who use excel as your spreadsheet for designing, how would u rate excel for structural calc.? and how i can start? is there any book would u recommend? i've been using mathcad and tedd's, but i have many excel applications i used as well, excel seems easy but doesn't check units as the other programs i use, please help

 

[GregLocock]

I share your concerns. Since it would be easy to include logic that gives the wrong answer for just a small range of inputs it seems to me that you could not pick up a third party sheet and use it for any mission critical calculations.

On the other hand, everyone has a copy and it is a great tool.

Cheers

Greg Locock

 

[IFRs]

My 2 cents:

For designing and structural calculations, I prefer NOT to use Excel, primarily because the formulas are hidden within the cells, logic paths are hard to follow if the program has to branch several times, there are limited functions available so you have to build your own and debugging is a pain in the rear.

I prefer to use MathCad, where the formulas are visible and "live", editing and debugging chores are easier and there are an enormous breadth of built-in functions to choose from.

I have heard that Mathematica is in the same class as MathCad.

MathCad also produces excellent ouptut that is easier for others to review and understand.

 

[IFRs]

Oh yes - you can use units in MathCad - a HUGE benefit, especially in the debugging stage.

 

[cuky2000]

Excel has many useful capabilities especially with table and form templates that made easy some calculations. However, is very limited for other complex calculations or engineering report.

Mathcad allow users to dynamically link a data source from Excel worksheet with application files. This capability to combine the good features of Excel makes Mathcad very powerful for many engineering application.

 

[IRstuff]

Not only can you include units in Mathcad, but you can also do unit conversion on the fly. Onve you've calculated a quantity, it's trivial to get the answer in another unit system.

The only really annoying thing is that Mathcad's plotting capabilities are still pretty much in the Stone Age, with the exception that the 3-D plots can be manipulated live. TTFN

 

[MALY]

Thanks guys, I have the same feelings, I like excel but it is scary to use it sometimes

 

[IRstuff]

If anything, it should be less scary than Mathcad.

There are easily 10 times more people beta-testing, oops, I meant using, Excel than Mathcad.

This makes Excel much more likely to work correctly. It's sad, but true. TTFN

 

[chichuck]

I'm not a regular Mathcad user, I've been working with Excel for a number of years. I tried Mathcad, and I'm more comfortable with Excel, for the following reasons:

1) it does works with tables better, in structures, I use many tables, many more than nice, closed form equations.

2) I can do a good job of getting error messages, notes and the like to appear or not appear using some if tests with text and "" values in them. To me this is very important for an engineering calculation. I can't do this very well in Mathcad.

3) Since I work in the US, units are not a big problem for me, I usually work in imperial units. When I do try and use a metric or SI unit, I can often do that merely with some if tests as well. Not pretty, not elegant but it works.

4) I don't have much trouble with equations being buried in cells. I tend to not use a lot of branches in spreadsheets, I prefer to use a lot of if tests, so those branches that were mentioned don't occur. Another thing I do is use labels in cells to display the equations I'm using, so a user or a checker can see them.


Regards,

chichuck

 

[IFRs]

While I agree that Excel is a great tool, from the perspective of producing output that a customer (or another engineer) can read and understand, MathCad suits me better. I also find that when I go back to an Excel spreadsheet that I have not dealt with for 6 months, it takes more time to visualize the methodology than from an old MathCad document.

 

[mloew]

MALY,

Interesting thread. I use MS Excel and MathWork's MATLAB for most "programming" type problems. These two packages share the limitation of visualizing the formulas like MathCAD can. It is a bit clumsy, also type the formula out as best I can in the cells adjacent to the adjacent cell for a bit more clarity in excel.

One question, though, what is "tedd's" that you refer to in your initial post.
Best regards,

Matthew Ian Loew

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[GregLocock]

Anyone who is looking for a free alternative to Matlab is well advised to check out Scilab, which has been ported to Windows. I think that scilab is actually easier to use than Matlab, but have no experience in running large or complex calculations in it. Some of the demos are amazing.

http://www.scilab.org/

My take on Excel is that it is fine for designing stuff iteratively, but the final answer needs to be validated by some other means, except in the most trivial case.



Cheers

Greg Locock

 

[MALY]

Tedd's is spreadsheet program using MS word, it is adds on to word , it is very good , you can check it at

http://www.tedds.com

 

[chichuck]

I wonder, how would all of you do the following in Mathcad:

when calculating wind loads on a building or structure, using ASCE 7-98 or 7-02, part of the process involves pulling numbers out of the table in Figure 6-6. It involves reading numbers in a table, and interpolating them. No equations are given, only the table values.

I can do this, abeit a bit awkwardly in Excel. How would you read this table in Mathcad, then interpolate between the lines and columns of numbers in the table?

Part of the table is reproduced here:

Values of External pressure coefficients, Cp

Theta

h/L | 10 15 20 25 30 35 45 60
-----+---------------------------------------------
0 | -0.7 -0.5 -0.3 -0.2 -0.2 0 0 0
0.25 | -0.7 -0.5 -0.3 -0.2 -0.2 0 0 0
0.5 | -0.9 -0.7 -0.4 -0.3 -0.2 -0.2 0 0
1 | -1.04 -1.0 -0.7 -0.5 -0.3 -0.2 0 0



Regards,

chichuck

 

[IRstuff]

Somewhat similarly. In Excel, there are lookup functions that you would use to find the closest value.

Mathcad has a similar approach, with the exception that you can then use the table to interpolate between values. There is a sample sheet for the ASCE wind load calculation somewhere, but I haven't been able to locate it. TTFN

 

[chichuck]

IRStuff,

But I'm not looking for the closest value, I want to interpolate between table values, say for h/L = 0.33 and theta = 22 degrees.

This I am able to do in Excel, but awkwardly, as I said.

What functions in Mathcad are you talking about that would be used to interpolate between the table values for h/L = 0.33 and theta = 22 degrees?

chichuck

 

[IRstuff]

Mathcad has 2 built-in interpolation functions, interp and linterp.

Linterp is the linear interpolation.

Interp uses a vector generated by any of 3 spline functions, lspline, pspline, cspline. They're all essentially the same, except for how they deal with endpoints, e.g., linear, parabolic or cubic.

If you search the Mathcad Collab at

http://collab.mathsoft.com/~Mathcad2000

there was a discussion in the last 6 months on how to do a 2-D interpolation as well, but it's essentially running the spline fit in 2 dimensions. TTFN

 

[cuky2000]

Check in MathCad Resource Center on Data Analysis the example for Two-Dimensional Spline Interpolation example.

With some modifications you should be able to do the work.

Good Luck

 

[paron]

In addition to "hiding" formulas, one other "security" issue arises with Excel.

If you keep a spreadsheet under your own control, then it is just a programmable calculator.

If everyone has their own copy of the spreadsheet or access to the original (shudder,) you are never quite sure that someone hasn't gone beyond altering the inputs (OK) to altering the formulas (maybe NOT OK.) And it is cumbersome at best to "audit" a spreadsheet to find out whether it is still valid.

The upshot? Fine as a scratchpad, but for any work which must be traceable or verifiable, don't use a spreadsheet, it is a lawsuit waiting to happen.

Ron

 

[chichuck]

IRstuff & cuky2000, linter looks like the trick. I'll try that. Thanks a lot.

Paron, I have a couple of thoughts on your remarks. First, it is possible to lock an excel worksheet so it cannot be changed, and protect that lock with a password. You can selectively unlock cells where input data will go. I've gotten spreadsheets that are like this off of the web. It seems like a good way to solve the problems you mention. Second, it seems to me that all those same issues will be present with a Mathcad file. You weren't trying to suggest otherwise were you?


regards,

chichuck