Im reading over about the directional derivative.(adsbygoogle = window.adsbygoogle || []).push({});

Stewart, page 800 says:

"Proof: If we define a function g of the single variable h by

[tex] g(h) = f(x_0 + ha, y_0 + hb) [/tex]

then by the definition of a derivative we have

[tex] g'(0)= lim_{h \rightarrow 0} \frac{g(h) - g(0)}{h} = lim_{h \rightarrow 0} \frac{f(x_0+ha, y_0+hb)-f(x_0,y_0)}{h} [/tex]

end quote

Is it me, or is he over using the variable h? He defines a function called g(h). And then he puts h back into the derivative. if h=0, then it does not make sense to say g(h)-g(0), becuase he said before that h=0. Should he call the function g(h), g(h'), and then he can call the h in the limit, plain old h?

**Physics Forums - The Fusion of Science and Community**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Directional Derivative

Loading...

Similar Threads for Directional Derivative | Date |
---|---|

I Directional Derivative demonstration | Jan 1, 2018 |

I Directional derivative | Mar 7, 2017 |

I A directional, partial derivative of a scalar product? | Feb 5, 2017 |

I Directional derivative: identity | Nov 23, 2016 |

I Problem with directional derivative | Jul 1, 2016 |

**Physics Forums - The Fusion of Science and Community**