for loop counter

#1 Posted: 10/11/2017 2:17:44 PM

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Hi,
I wish to loop through the YR formula, in pic below, for values of z being 0,0.2,0.4,0.6,0.8,1.0,1.2,1.4,1.589.
My progress so far is to produce an array evenly spaced z values and if the 1.0001 factor is not applied to hc_full then the last element of the z array is 1.362, rather than 1.589.
It is obvious to me that I have some missing skill here, please throw me some hints.

Regards, Tim

#2 Posted: 10/11/2017 3:25:59 PM

Jean Giraud

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Just define your 'x' vector of values, include in small loop.

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#3 Posted: 10/11/2017 3:49:55 PM

timgow

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Hi Jean,
Thank you for the example file, I will study this for better understanding.
I have longer arrays to create also so wish to automate; if I make z as in the pic or with equal spacing, is there a means of appending the final (1.589) value to the end of the array?
Tim

#4 Posted: 10/11/2017 5:42:16 PM

CBG

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I do not see any problem.

#5 Posted: 10/11/2017 10:22:09 PM

Jean Giraud

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Wrote
I have longer arrays to create also so wish to automate;

If you have longer array, equally spaced => as easy.
Naturally, if not equally spaced, must be manual.

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#6 Posted: 10/11/2017 10:28:28 PM

Jean Giraud

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... if they are not equally spaced, but if there is a bit
of logic in the spacing, we can select from a list that
can be made/refactored as you wish at will from a little
counter loop.

#7 Posted: 10/12/2017 5:28:21 AM

timgow

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Jean,
Thank you for the counter loop example, this will stretch my programming comprehension.

CBG,
Thank you for typing the work from scratch, and showing no issue with the 1.589 value.
I redefined hc_full immediately above the z range call and then the output changed to match your results.

The hc_full is defined with an if statement.

The 1.589 value is absent from the z range.

The hc_full is redefined directly above the z range call (to override the value produced by the if statement) and the 1.589 value is now present in the z range.

Have I contravened a working principle in some way?

Tim

#8 Posted: 10/12/2017 5:38:09 AM

timgow

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Redefining hc_full using hc_full:=hc_full also fixes the z range array.
Tim

#9 Posted: 10/12/2017 1:05:33 PM

Jean Giraud

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Wrote
Have I contravened a working principle in some way?

Maybe not ? work sheet would help and no help.
Smath 6179 does not take index on the RHS.

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#10 Posted: 10/12/2017 5:45:07 PM

Martin Kraska

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for(3)-loops with initial, second and maximum value aren't robust if floating point values are specified. The internal representation of such numbers may differ from what is displayed due to round-off.

Due to this it is not good programming style to test the equality of two floating point numbers without specifying a tolerance. If you want to be safe, you either introduce such a tolerance or you generate the list of values based on a list of integers.

It should be possible to modify for(3) such that the tolerance is generated as a fraction of the difference between first and second value.