Looping the root function 1

[cjm2176]

Hi,

I want to find and save the root of a function, make a small change to a parameter in the function and find the new root.

I defined the parameter over an interval, but MathCAD's root function doesn't like this (I get a message that says root only works with matrices or scalars), though there are no errors if I define the parameter with only one value.

I also tried using a for loop to evaluate the root, but MathCAD doesn't give either an output or an error, nothing happens.

Is there another way to go about this?


Thanks!

 

[Mike1984Armstrong]

Can you post a worksheet?

Regards

Mike

 

[cjm2176]

Here is the sheet

I am actually now getting an error saying that the variable which I chose to be the argument in my function is undefined.

thanks

 

[IRstuff]

>> Nowhere do you define beta.nd, so why is it a surprise that it's flagged as undefined?

>> Your construct of k.nd is interesting, but not necessary. Do:

i:0,1;10
k.nd[i:i/10

this will create an indexed variable k.nd

Also, you need to define beta.nd somewhere near the top of the sheet.

Then, you do

r0[i:root(f(beta.nd,k.nd[i),beta.nd)

TTFN

FAQ731-376

 

[IRstuff]

My attempt to "fix" your sheet

TTFN

FAQ731-376

 

[cjm2176]

Thanks! your explanation was very logical, and much easier than creating loops

Since I beta.nd was the argument to my function, I thought it did not have to be defined

 

[IRstuff]

It's an argument, yes, but when you call the root function, it needs a starting guess value to start the root finding algorithm.

TTFN

FAQ731-376