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Nov 18, 2018
04:46 PM

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Nov 18, 2018
04:46 PM

odesolve "array index invalid"

Hi, I am trying to solve a simple differential equation that uses an excel acceleration vs time as the driving force. I have used linterp to ensure that time values used in the solve can be extracted from the input acceleration versus time data.There also seems to be an issue with too many initial conditions. I would have thought you need 4 but this solve block only seems to need 3?

Any assistance would be appreciated.

Thanks

ross

Solved! Go to Solution.

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Nov 19, 2018
07:00 AM

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Nov 19, 2018
07:00 AM

@remslie wrote:

Hi, I am trying to solve a simple differential equation that uses an excel acceleration vs time as the driving force. I have used linterp to ensure that time values used in the solve can be extracted from the input acceleration versus time data.There also seems to be an issue with too many initial conditions. I would have thought you need 4 but this solve block only seems to need 3?

Any assistance would be appreciated.

Thanks

ross

I think you have confused the system (x) with the base (y) at times! Here's my modification:

Alan

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Nov 19, 2018
07:00 AM

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Nov 19, 2018
07:00 AM

@remslie wrote:

Hi, I am trying to solve a simple differential equation that uses an excel acceleration vs time as the driving force. I have used linterp to ensure that time values used in the solve can be extracted from the input acceleration versus time data.There also seems to be an issue with too many initial conditions. I would have thought you need 4 but this solve block only seems to need 3?

Any assistance would be appreciated.

Thanks

ross

I think you have confused the system (x) with the base (y) at times! Here's my modification:

Alan

Nov 19, 2018
07:49 AM

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Nov 19, 2018
07:49 AM

Alan,

Many thanks once again for your prompt response and dedication to the Mathcad cause.

Best regards,

Ross