fmax function?

[Guest]

hi,
i was wondering if there's a function in excel that
allows you to calculate the maximum and minimum of a
particular function. for example, in my ti-83, i can type
in fmax(sin(x),x,0,360) to determine the x for which the
sin(x) function has its max. in this case, it yields 90,
which is where the curve has a top height of 1. is there
any similar type of function for excel? i've tried
the "max" function in excel, but that seems not to work
as it is only for calculating the highest value in a
group of cells and not within a function itself. any help
would be greatly appreciated. thanks!

 

[hgrove]

Anonymous wrote...

i was wondering if there's a function in excel that allows you to
calculate the maximum and minimum of a particular function. . . .

...

This is *NOT* what spreadsheets do. It appears you want more of
symbolic math package.

Anyway, you could use Solver. Enter the following formula in A2.

A2:
=SIN(RADIANS(A1))

Then with A2 selected, run the menu command Tools > Solver, set 'Equa
to' to Max, and enter A1 as 'By Changing Cells', and click on Solve

 

[Bernie Deitrick]

Hi,

You need to be a little creative, but if you can stand some inaccuracies sue
to step size, you can use the an array entered formula (enter with
Ctrl-Shift-Enter). For your example:

=DEGREES(ASIN(MAX(SIN(RADIANS(ROW(A1:A360))))))

The step size is 1 (in this case, degrees): to decrease the step size,
change the ROW(A1:A360) to (ROW(A1:A3600)/10), for example.

HTH,
Bernie
MS Excel MVP

 

[hgrove]

Bernie Deitrick wrote...

You need to be a little creative, but if you can stand some
inaccuracies sue to step size, you can use the an array entered
formula (enter with Ctrl-Shift-Enter). For your example:

=DEGREES(ASIN(MAX(SIN(RADIANS(ROW(A1:A360))))))

The step size is 1 (in this case, degrees): to decrease the step
size, change the ROW(A1:A360) to (ROW(A1:A3600)/10), for
example.

...

I may be wrong, but I'd assumed the OP was using a simplified exampl
with an obvious and well-known answer. Anyone who remembers an
trigonometry should remember that SIN (and COS) are bounded function
with periodically repeating maximums and minimums. For SIN, maximum
for argument PI/2 + 2*N*PI, minimum -1 for argument PI/2 + (2*N+1)*PI
or 90 and 180 plus integer multiples of 360 in degrees.

In the general case, e.g., arbitrary coefficient polynomials wit
mutliple sign changes, step size is everything

 

[Guest]

Hi,
Thanks for the suggestion! It seems to work great.
Thanks again!

 

[Guest]

Just out of curiosity, does Microsoft Access also have a
fucntion similar to Solver where we can calculate max and
min values? Thanks for your help again!

 

[Harlan Grove]

Just out of curiosity, does Microsoft Access also have a
fucntion similar to Solver where we can calculate max and
min values? Thanks for your help again!

....

No.