derivatives of a parametric equation
07-22-2018, 11:17 AM
Post: #1
 DrD Senior Member Posts: 1,133 Joined: Feb 2014
derivatives of a parametric equation
Is there an hp prime command for finding derivatives of parametric equations, with respect to a parametric variable?

For example, find the second derivative of a parametric equation where:
x = t² - 4;
y = t³ - 3*t;

Result: d²y/dx² = (3*t²+3) / (4*t³);

-Dale-
07-22-2018, 03:26 PM
Post: #2
 Aries Member Posts: 159 Joined: Oct 2014
RE: derivatives of a parametric equation
07-22-2018, 04:58 PM
Post: #3
 parisse Senior Member Posts: 1,317 Joined: Dec 2013
RE: derivatives of a parametric equation
Code:
 y1:=diff(y,t); x1:=diff(x,t); normal(diff(y1/x1,t)/x1);
Since x1=dx/dt and y1=dy/dt, dy/dx=y1/x1, then d2y/dx^2=d(dy/dx)/dx=d/dt(dy/dx)/x1
07-23-2018, 09:15 AM
Post: #4
 Aries Member Posts: 159 Joined: Oct 2014
RE: derivatives of a parametric equation
image share

Best,

Aries
07-23-2018, 09:25 AM
Post: #5
 DrD Senior Member Posts: 1,133 Joined: Feb 2014
RE: derivatives of a parametric equation
Thank you Parisse, (and Aries). I was looking for a single pre-existing command that would perform this operation, (in the toolbox catalog). I didn't find anything specifically, but there is always the chance I might have missed it!

-Dale-
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