Plotting a function with a given range of values.

I understanding the basics of plotting an equation but for some reason I cannot get this work. I want to plot the equation for friction factor f=1/(1.8*log10(6.9/Re + (relr/3.7)^1.11))^2 in the range 2300<Re<2e7.

 x = linspace(2300, 2e7, 100);
y = (1/(1.8*log10(6.9/x + (0.000965)^1.11)))^2
plot(x,y)

[Elias Gule]

This will most probably give you an error.

Remember x is a vector. So you should use element-wise division "./" instead of "/". Even the squaring, you need to replace ^2 with .^2.

Answer 1

[Paul Shoemaker]

X is a vector in this case, so you have to alert Matlab to treat it on a per-element basis with the use of "." before division/multiplication/power operations.

y = (1./(1.8*log10(6.9./x + (0.000965)^1.11))).^2

Paul Shoemaker

http://www.matlabinvesting.com