Newton's Method utilizing Mathcad

  • #1
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Homework Statement


I am writing a simple program in Mathcad for Newton's Method. The function is x^3-5*x^2+3*x+4. The root is between 0 and 3, and we want a tolerance of 0.00001. My code is the exact same as a program I made in Matlab that works, but since I am new to Mathcad, I am getting an error that I do not know how to fix.

The error I receive is "This value must be a scalar"; it is referring to my function f(x). Here is the code:

upload_2015-1-21_8-21-53.png
 

Answers and Replies

  • #2
gneill
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I don't see why you're making the assignments g(x) ← f and dg(x) ← df. I figure that this is where Mathcad is tripping up because it can't tell at the outset what f is and decides that it's a scalar.

If you get rid of those two assignments and just use f(x) and df(x) inside your function you should be fine.
 
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  • #3
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That certainly fixed it! It definitely was redundant and unnecessary. Thanks!

One other question: do you know a way of implementing Boolean OR in Mathcad? I want to remain in a while loop if any of 3 statements are true. This is rather easy in Matlab, but I am finding it difficult in Mathcad. I am uncertain as to why Mathcad did not include this.
 
  • #4
gneill
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Open the "< ≠ ≥" menu by clicking the icon with the same designation (I have Mathcad 11.2, but presumably the same feature exists in whatever version you are using). You'll find boolean operators there.
 
  • #5
798
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Ah, I didn't realize that the V represented OR. Thanks a bunch!
 

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