I WANT TO SOLVE A EQUATION USING MATLAB.....

x=arccosd((pi/(2*N))*(sqrt(1+(N*delT/pi)^2)));
delT=((((2*n)+1)*pi)*(lam-lamc))/(lamc);
solve(((pi*cosdx*sindNx)/(2*N*sindx))== 0.7071);

WANT TO SOLVE FOR "lam" INTERMS OF "delT" , "n" , "lamc" , "N"

PLEASE HELP ME......

[Walter Roberson]

Please read the guide to tags and retag your question.

http://www.mathworks.co.uk/matlabcentral/answers/43073-a-guide-to-tags

[Walter Roberson]

Is 0.7071 representing 1/sqrt(2) ?

Answer 1

[Walter Roberson]

I would suggest that cosdx should be cosd(x), that sindNx should be sind(N*x), and that sindx should be sind(x)

You should probably define delT first, and then x in terms of that, and then solve().

Be sure to syms all symbolic variables.

When you do the solve() be sure to specify which variable you want to solve for.

[Walter Roberson]

Can we presume that n and N are integers? Any further restriction on their values?

[Walter Roberson]

Presuming that n and N are integers, then the limits where the expression is real-valued are

lamc * (1 +/- sqrt(4*N^2-pi^2)/((2*n+1)*N*pi))

Note that this is itself complex-valued when N = -1, 0, or 1: there are no real-valued solutions for those N.

As N increases in absolute value, the second part of the expression gets smaller, with the effect of pulling the roots of the overall equation tighter to lamc. At some point, though, N^2 will be much greater than pi^2, leading to the real-valued boundaries being at approximately

lamc * (1 +/- 1/((2*n+1)*pi))