calculation problem!

[PETER_AUT]

In my program there are several calculations. The dates are from a curve (picture in the attachement) and with the dates from the data i want to make  a bendingstrenght-calculation.

When i type random numbers( for example x=(10,20,30,40,50,60,70), y=(0,5;0,6;0,7;0,8;0,7;0,6;0,5) like a curve) and start the program, the resulting numbers are false.

Could somebody check my calculation, please?!

TNKS

Best regards,

Peter

Calculation Information:

***************************

A=(MG*(ML - XL)) / ML

XL=ML / 2

RANGE for M:

0 <= x <  XL                --->        M(x) =A*x

XL<=x<=ML                 --->        M(x) =A*x - MG*(x - XL)

Bendingstrength E*J (x) = M(x) / f''(x)

With the dates from the x and y arrays i calculate the second derivative. To calculate the second derivative, i calculate the gradient of the dates ( picture of the formula in the attachement) two times.

gradient = 1st derivative

the gradient of the 1st derivative = 2nd derivative 

[PETER_AUT]

HI!

Does anybody know a Subvi, which calculates the derivative from X,Y-points???

Best regards,

Peter

[tst]

If I remember my calculus correctly, a derivative is simply the tangent of the function at any specific point. If you have 2 points, you can, presumably, find the difference between the Y values and between the X values and divide to get the tangent.

If this doesn't help, the Analyze palatte probably has some VIs that do derivatives. You can also search the function palettes or the example finder.

[Will.D]

There's a number of calculus VIs in Analyze->Mathematics->Calculus...  but tst is right too.  The (instantaneous) derivative is just the tangent at that point

[PETER_AUT]

Thank you guys for your fast answers!

I have found a SUBVI, called derivative.

It*s in the ANalyze --- Signal Processing --- Time Domain palette!

Thank you!

Best regards,

peter