csqrtf, csqrt, csqrtl

[edit] Parameters

[edit] Return value

If no errors occur, returns the square root of z, in the range of the right half-plane, including the imaginary axis ([0; +∞) along the real axis and (−∞; +∞) along the imaginary axis.)

[edit] Error handling and special values

Errors are reported consistent with math_errhandling

If the implementation supports IEEE floating-point arithmetic,

• The function is continuous onto the branch cut taking into account the sign of imaginary part
• csqrt(conj (z)) == conj (csqrt(z))
• If z is ±0+0i, the result is +0+0i
• If z is x+∞i, the result is +∞+∞i even if x is NaN
• If z is x+NaNi, the result is NaN+NaNi (unless x is ±∞) and FE_INVALID may be raised
• If z is -∞+yi, the result is +0+∞i for finite positive y
• If z is +∞+yi, the result is +∞+0i) for finite positive y
• If z is -∞+NaNi, the result is NaN±∞i (sign of imaginary part unspecified)
• If z is +∞+NaNi, the result is +∞+NaNi
• If z is NaN+yi, the result is NaN+NaNi and FE_INVALID may be raised
• If z is NaN+NaNi, the result is NaN+NaNi

[edit] Example

#include <stdio.h>
#include <complex.h>
 
int main(void)
{
 double complex z1 = csqrt(-4);
 printf ("Square root of -4 is %.1f%+.1fi\n", creal (z1), cimag (z1));
 
 double complex z2 = csqrt(conj (-4)); // or, in C11, CMPLX(-4, -0.0)
 printf ("Square root of -4-0i, the other side of the cut, is "
 "%.1f%+.1fi\n", creal (z2), cimag (z2));
}

Square root of -4 is 0.0+2.0i
Square root of -4-0i, the other side of the cut, is 0.0-2.0i

[edit] References

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