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ptc-42546051-Visitor
1-Visitor
April 18, 2012
Solved

ln function not working in Solver

  • April 18, 2012
  • 2 replies
  • 3678 views

I am mildly interested in knowing what abstruse, hypercomplex, super-sophisticated reason Mathcad has for screwing up a simple calculation.

The equation is this:

-1.99*298*ln(x)= -1.85*10^4

The equals sign is the Boolean equals. Invoking Solver to solve for x produces an answer that makes no sense whatsoever.

Spreadsheet attached as MathCad 12 file. Note below I have solved the problem myself. At least MathCad gets the right answer then.

The makers of MathCad do understand their program is being used to build bridges, airliners, and skyscrapers, right?

Best answer by Fred_Kohlhepp

One of us needs a refressher in naatural logs!

2 replies

W
wayne12-Amethyst
12-Amethyst
April 18, 2012

Works fine in 11, 14 and 15.

I don't have 12.

Could you post a picture of what you get in 12?

tmp10.gif

F
Fred_Kohlhepp23-Emerald IAnswer
23-Emerald I
April 18, 2012

One of us needs a refressher in naatural logs!

P
ptc-42546051-VisitorAuthor
1-Visitor
April 18, 2012

The problem is my 54-year-old eyes.

I did not see the "e13" at the end. I made the text bigger, you'll notice, but I still haven't found out how to make the numbers bigger. Surely that will be in the manual somewhere.

*off to make the number default font size bigger. somehow*

Thank you both for your help.

Jeff Corkern

M
mzeftel1-Visitor
1-Visitor
April 18, 2012

To make the default math bigger in versions of Mathcad up to 15, just click on a number and change the constants size to whatever you want in the toolbar. All numbers will change to the same size. Then click on a letter in math, and change the variables size to the desired size.

You can also go into the Format > Equations, and choose either Variables or Constants, then modify the size.

Mona

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