Puls train for stepper motor

I need to generate variable freq pulses to drive stepper motor
When i use delaymicros (x) it take to long time to calculate x*``
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it take to long time to calculate x

How are you calculating x? Post the code, using code tags ("</>" button).

Have a look at this Simple Stepper Code - the second example uses millis() and micros() rather than delay().

...R Stepper Motor Basics

There are several approaches to generating accelerating pulse trains, most notable time domain and frequency domain. I presume you are using square roots for the time-domain approach? With floats?