Plotting 3D with two functions

I have two functions (a,b,c,...,f are constants):

y(x) = ax^5 +bx^4 +cx^3 +dx^2 +ex + f

z(x) = a2x^5 +b2x^4 +c2x^3 +d2x^2 +e2x + f2

For the above I have a X-Y plot and a X-Z plot(the X axis is the same for both). I want to know how can I create a 3d plot that shows both coordinate systems. I would really aprecciate if anyone can code a solution

[Walter Roberson]

fplot3(@(x)x, @(x)  ax^5 +bx^4 +cx^3 +dx^2 +ex + f, @(x) a2x^5 +b2x^4 +c2x^3 +d2x^2 +e2x + f2)

Except that you have to adjust the syntax on the polynomials because MATLAB has no implicit multiplication.

[Luis Francisco Sanchez]

Thank you very much. I have another doubt... If I have a compound function for y and z (it changes between specific intervals), how can I define the parameters for the different intervals in the plot?

[Walter Roberson]

If you use the Symbolic Toolbox you can use piecewise()

If you are working numerically, then there is a trick that can often (but not always) be used:

result = (condition1) .* (expression_that_applies_when_condition1_is_true) + (condition2) .* (expression_that_applies_when_condition2_is_true);

for example,

y = (x>=0 & x<=5) .* (x.^2-5*x+3) + (x>5 & x<10) .* (3+sin(8*pi*x))