cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Showing results for 
Search instead for 
Did you mean: 

How to produce a log based range variable or plot equation with vector as independent variable?

jgillen1
1-Newbie

How to produce a log based range variable or plot equation with vector as independent variable?

Hello, 

I am working on a project, but can not find a way to produce a decent log plot over a large range. The issue is that if I use the log function under plots with a range variable for my x values there will be too few data points on the low end of the plot to look smooth. So I tried making a log-based x set of data using a range variable converted to a power based set of vector data, variable d, but the when plotting it says can not divide by zero. Though after multiple checks, I do not believe my d values ever goes to zero. I just need to be able to make a plot of y vs log(x) able to span a range of 10^-10 to 10^-3 meters and have sufficient data points for the small x values. 

Also getting this error now for the second attempt, Plotting failed. Replace complex values and NaNs by real numbers.

problem.PNGProblems.PNG 

 

1 ACCEPTED SOLUTION

Accepted Solutions
LucMeekes
23-Emerald I
(To:jgillen1)

Use the function logspace(min,max,npts) which creates a vector of values from min to max with npts point over the entire range.

Example (to get 5 points per decade):

LM_20171108_logspace.png

 

Success!
Luc

View solution in original post

5 REPLIES 5

I usually create a range variable,  i := 3, 3.3 . .8

then plot 10^i

LucMeekes
23-Emerald I
(To:jgillen1)

Use the function logspace(min,max,npts) which creates a vector of values from min to max with npts point over the entire range.

Example (to get 5 points per decade):

LM_20171108_logspace.png

 

Success!
Luc

View solution in original post

Ok, will try this.

Is there a way to add units. Can not seem to get units into the logspace values? If I put them in just ignores them on the output.

Oh, putting it on the outside of the parentheses works. Thanks again!

Announcements
Check out the latest
Mathcad Tip
"PTC Mathcad 15 / Prime 1-6 Update."